I N S I D E T H I S I S S U E

December/décembre 2000 Volume/volume 94 Numbers/numéros 6 [685]The Journal of the Royal Astronomical Society of CanadaLe Journal de la Société royale d’astronomie du CanadaI N S I D E T H I S I S S U ESpace Surveillance Research • Space Mirror Safety • Teaching Astronomy 101CASCA Abstracts • How the Sun Shines

December /décembre / 2000Vol. 94, No. 6 Whole Number 685contentstable des matièresFEATURE ARTICLES/ARTICLES DE FOND213 The Space Surveillance Research andAnalysis Laboratoryby Michael A. Earl219 How the Sun Shinesby John N. Bahcall228 Transient Phenomena on the Moonby Patrick Moore229 A Lamplighter Moment: Daytime Observationsof Venus at Inferior Conjunctionby Fr. Lucian J. Kemble, OFM (with comments byDavid M. F. Chapman)COLUMNS/RUBRIQUES232 Reflections: New Year’s Dayby David M. F. Chapman235 Second Light: Of Pale Kings and Pyramidsby Leslie J. Sage259 At The Eyepiece: Royal Reflectionsby Guy Mackie261 Orbital Oddities: Conjunction Junctionby Bruce McCurdy263 Scenic Vistas: Beyond the Orion Nebulaby Mark BrattonRESEARCH PAPERS/ARTICLES DE RECHERCHE237 Space Mirror Experiment: A Potential Threatto Human Eyesby James G. Laframboise and B. Ralph Chou241 Photoelectric Magnitude Measurements ofMars Made During the 1998–2000 Apparitionby Richard W. Schmude Jr.246 Abstracts of Papers Presented at the 2000CASCA Annual Meeting Held at Universityof British Columbia, Vancouver, May 25 toMay 28, 2000EDUCATION NOTES/RUBRIQUES PÉDAGOGIQUES252 Improving the Teaching of Astronomy 101Through Tutorialsby Wayne A. Barkhouse and Chris R. BurnsThe Space Surveillanceand Analysis Laboratoryp. 213Space Mirror Experimentp. 237How the Sun Shinesp. 219At the Eyepiecep. 259The Journal of the Royal Astronomical Society of CanadaLe Journal de la Société royale d’astronomie du Canada

DEPARTMENTS/DÉPARTEMENTS206 President’s Cornerby Robert F. Garrison208 Editorialby Wayne A. Barkhouse209 Correspondence / CorrespondanceA Life of Variable Stars; Medicine Wheels210 News Notes / En manchettesWeather Forecasts for Canadian Astronomers;Where are Earth’s Trojans?; SOS (Saving OshawaSkies); More Tagish Lake Meteorite Surprises;Prairie Meteorite Search – Two Up!234 From the Past / Au fil des ansThe Length of the YearNews Notesp.210ACROSS THE RASCDU NOUVEAU DANS LES CENTRES255 Society News / Nouvelles de la Sociétéby Kim Hay – RASC Award for Excellence inAstronomy; Congratulations; Asteroid Boltwood256 Astronomical Society of the Pacific AwardsMaria and Eric Muhlmann Award; AmateurAchievement Award257 A Candle in the Darkby Bill Broderick265 Index to Volume 94, 2000Society Newsp. 255AstroCryptic Solutionp. 268Cover:The largest pyramid, at the centreof the photograph, is the GreatPyramid of Giza, which was builtas a tomb for the Egyptian KingKhufu (also known as Cheops).Photograph courtesy ofKate Spence

President’s Cornerby Robert F. Garrison (garrison@astro.utoronto.ca)After 13 years of searching, the pulsar powering Shelton’sSupernova finally has been found (Middleditch et al.2000, New Astronomy, 5, 243). The elusive pulsar remnantof Supernova Shelton 1987A is rotating with a period of 2.14milliseconds, which is not the fastest known. Can you imaginea compact object so dense that only neutrons can exist in it? Ifyou can imagine that, stretch your mind to picture an objectmore massive than the Sun squeezed into a sphere of diameterabout 30 km (give or take a few), rotating almost 500 timesevery second. These are interesting times for being involved inastronomy.Canadian Ian Shelton, the supernova’s discoverer, wasResident Observer at the University of Toronto SouthernObservatory (UTSO) on Cerro Las Campanas in the desertmountains of Chile. In the last semester of his four-year stint(1981-1983, 1985-1987), he spotted the supernova, which wasthe brightest since 1604, five years before the first use of atelescope. His claim to credit for the discovery is supported byphotographic evidence: before and after plates of the LargeMagellanic Cloud taken twenty-four hours apart. He used anancient ten-inch, wide-angle telescope stopped down to fiveinches to improve the images for that first exciting night. Thediscovery images were followed by the first photoelectricphotometry of the rapidly brightening supernova, using theUTSO 60-cm telescope. The next night, observers far enoughsouth to see it at –69 degrees were looking at it and takingwhatever data they could. Ian observed it every clear night fromFebruary 23 until July 1, sometimes changing instruments severaltimes per night. A very large telescope would not have had therequired observing time available, and instrument changes areoften difficult and time consuming on the largest facilities.At the UTSO, the late Jerry Kristian of the CarnegieObservatories installed a specially designed, high-speed photometer(referred to as The Black Box) for detecting the remnant, probablya pulsar, which was expected to have a period of order 1 millisecond(ms). Ian checked for it once every clear night for as long as thesupernova was visible with the UTSO telescope, which turnedout to be about a year and a half. After that The Black Box wastransferred to the 4-meter telescope at the Cerro TololoInterAmerican Observatory and used occasionally, but not everyclear night. A 0.5-ms periodicity was later detected but discountedas an artifact of the equipment used.My point here is to emphasize that not all discoveries aremade with huge telescopes by professional astronomers. In1987, Ian Shelton had only a B.Sc., though now he has a Ph.D.and is working at the giant 8.4-m Subaru Telescope. Also, it canbe argued that many other important discoveries are madeusing telescopes within the range of amateur astronomers. ForThe Journal is a bi-monthly publication of the Royal Astronomical Society of Canada and isdevoted to the advancement of astronomy and allied sciences. It contains articles on Canadianastronomers and current activities of the RASC and its centres, research and review papersby professional and amateur astronomers, and articles of a historical, biographical, oreducational nature of general interest to the astronomical community. All contributions arewelcome, but the editors reserve the right to edit material prior to publication. Researchpapers are reviewed prior to publication, and professional astronomers with institutionalaffiliations are asked to pay publication charges of $100 per page. Such charges are waivedfor RASC members who do not have access to professional funds as well as for solicitedarticles. Manuscripts and other submitted material may be in English or French, and shouldbe sent to the Editor-in-Chief.Editor-in-ChiefWayne A. BarkhouseDepartment of AstronomyUniversity of Toronto60 St. George StreetToronto, OntarioM5S 3H8, CanadaInternet: barkhous@astro.utoronto.caTelephone: (416) 978-2528Fax: (416) 946-7287Associate Editor, ResearchDr. Douglas HubeInternet: dhube@phys.ualberta.caAssociate Editor, GeneralMichael AttasInternet: michael.attas@nrc.caAssistant EditorsMichael AllenMartin BeechRalph ChouPatrick KellyDaniel HudinEditorial AssistantSuzanne E. MoreauInternet: semore@sympatico.caProduction ManagerDavid LaneInternet: dlane@ap.stmarys.caThe Journal of The Royal Astronomical Society of Canada is published at an annual subscriptionrate of $80.00 by The Royal Astronomical Society of Canada. Membership, which includesthe publications (for personal use), is open to anyone interested in astronomy. Annual feesfor 2000, $40.00; life membership is $800. Applications for subscriptions to the Journal ormembership in the RASC, and information on how to acquire back issues of the Journal canbe obtained from:The Royal Astronomical Society of Canada136 Dupont StreetToronto, Ontario, M5R 1V2, CanadaInternet: rasc@rasc.caWebsite: www.rasc.caTelephone: (416) 924-7973Fax: (416) 924-2911Contributing EditorsMartin Beech (News Notes)David ChapmanKim Hay (Society News)Bruce McCurdyHarry PulleyLeslie SageRuss SampsonDavid Turner (Reviews)Mary Lou Whitehorne (Education Notes)ProofreadersSteven BurnsJames EdgarMaureen OkunSuzanne MoreauDesign/ProductionBrian G. Segal, Redgull IncorporatedAdvertisingIssac McGillisTelephone: (416) 924-7973PrintingMacNab Printers Ltd.Canadian Publications Mail Registration No. 09818Canada Post: Send address changes to 136 Dupont St., Toronto, ON M5R 1V2We acknowledge the financial support of the Government of Canada, through the PublicationsAssistance Program (PAP), toward our mailing costs.U.S. POSTMASTER: Send address changes to IMS of NY, P.O. Box 1518, Champlain, NY 12919.U.S. Periodicals Registration Number 010-751.Periodicals postage paid at Champlain, NY and additional mailing offices.© 2000 The Royal Astronomical Society of Canada. All rights reserved. ISSN 0035-872X206JRASC December / décembre 2000

example, consider the large-scale structureof the universe which gave us the view ofthe “stick man” with bubbles (voids) andstrings. Margaret Geller and John Huchramade that discovery during an extensivesurvey using a small (60-cm) telescope.As in the case of the supernova, the detailshave been filled in using larger telescopes.Many large telescopes are being builttoday, and that is a good and wonderfulthing. The problem is that, in Canadaespecially, most of the capital and operatingfunds come with a zero-sum condition,which means building the large telescopestakes away the support of small andmoderate-sized telescopes, which are thefoot soldiers of the observational army.We are in danger of producing only 5-stargenerals. I’m very much in favor of buildingthe biggest and best instruments we can,but new money is needed. We can’t buildthese instruments on the current budget,even after decimating the budgets of thesupporting telescopes, which should notbe sacrificed. The recent Long RangePlanning Panel report, which requestsnew money, should be given the widestpossible distribution. Talk to your Memberof Parliament about it and stress the needfor new investment. Canada needs a balanceof telescope sizes and capabilities, for notall interesting objects are faint and notall faint objects are interesting.GREAT ASTROPHOTOS WANTEDA new feature coming to the Journal is a regular gallery where we will feature members’ astrophotographs. As well, wealways have a use for photos that can be used to illustrate articles in the Journal.For many of our members astrophotography is a passion. The search for the perfect shot of some faint fuzzy canconsume countless frigid nights and buggy evenings — as long as the sky is clear and dark, some RASC member is outthere shooting the stars and planets and other related phenomena such as aurorae and other atmospheric events.We invite you to send us your best shots. We can handle prints, transparencies (from 35mm to 810 inches), andhigh resolution digital or scanned images in most popular formats. Your image will most likely be printed in black and white,but if you have a great colour shot, send it along as we try to print at least one colour section per year.Contact the editors (addresses can be found on the masthead at the beginning of this magazine).December/ décembre 2000 JRASC207

Editorialby Wayne A. Barkhouse, Editor-in-ChiefMathematically speaking, the end ofthe current millennium is upon us.This is a natural time to reflect uponthe changes that have occurred in our societyduring the past one thousand years and toimagine what will happen in the future.Specifically, how has our knowledge ofastronomy evolved since AD 1000? What havebeen the most significant astronomicaldiscoveries during this period? What will theJournal editor write (or communicate bythought?) in December, AD 3000 about thepast 1000 years? We are alive at a special timein human history to be able to witness thebeginning of the new millennium.Looking back, what was the extent ofour knowledge of astronomy in AD 1000?Night-sky observations had been recordedfor centuries and many cultures developedindependent and sophisticated calendars.Greek science flourished for almost 1000 yearsfrom 600 BC and included quantitativemeasurements of the size of the Earth andrelative distances of the Moon and Sun.Geocentric models were developed to calculatethe positions of the planets. The model ofPtolemy was still in use by the Arabs in AD1000.The first significant breakthrough inhuman understanding of our place in theuniverse (since AD 1000) was the CopernicanRevolution — the notion that the Earth is notthe centre of the universe but instead orbitsthe Sun which is (near) the centre. Althoughone of the Greek philosophers, Aristarchus,had suggested this idea long before Copernicus,it was not until the late 16 th century that itfinally started to take root. The demotion ofthe Earth from the special place at the centreto being “just another planet” was one of themost important paradigm shifts to occur inthe history of the human race and was truly“revolutionary.”The next major advance took place inthe early 1600’s with the Dutch invention ofthe telescope and its use by Galileo forastronomical study. His discovery of the phasesof Venus, the moons of Jupiter, and the factthat the Milky Way could be resolved intothousands of stars showed how technologycould be used to improve our understandingof nature. Also during this time, Keplerdeveloped his three laws of planetary motion,laying important mathematical groundwork.The Copernican Revolution culminatedin 1687 with Newton’s publication of thePrincipia, unifying the work of Galileo andKepler in a set of dynamical laws that wereapplicable to objects on Earth or in the heavens.The motions of projectiles and planets couldnow be understood using a model that wasphysically and mathematically sound.In the last one hundred years, the paceof acquiring knowledge has increaseddramatically. Einstein’s General Theory ofRelativity initiated a major revolution in theway we view gravity and, along with his SpecialTheory of Relativity, superseded the work ofNewton. This occurred at a time whentechnology was beginning to make possiblethe building of large telescopes, which woulddramatically extend the observational frontiers.Hubble’s extragalactic work demonstratedthat the Milky Way was but one of many “starsystems” spread throughout an expandinguniverse, and could be understood in largepart by Einstein’s equations of General Relativity.In the 1930’s Hans Bethe discovered thatthe source of power for the Sun, and thereforeall stars, was nuclear fusion. With this theoreticalfoundation and the remarkable progress gainedin understanding the spectroscopicobservations, the field of stellar astronomyapproached a level of maturity that was onlydreamed of in the 19 th century.In the later half of the 20 th century, themost profound achievements have been broughtabout by our relentless drive to understandthe workings of our universe on the largestscales. The discovery in the 1960’s of the birthpang of the Big Bang, the cosmic microwavebackground, put a nail in the coffin of themajor rival theory at that time and placedcosmology on a strong scientific foundation.Today we find ourselves in a veryinteresting period. Observations indicate thatthe majority of matter in the universe doesnot radiate like ordinary matter but is instead“dark.” Also, recent high-redshift supernovaeand, independently, measurements of thefluctuations in the cosmic microwavebackground, imply that approximately 70%of the mass-energy of our universe may be insome form of a “repulsive-force” that causesthe rate of the expansion of the universe toincrease with time.What wondrous and profound discoverieswill occur in astronomy and astrophysics inthe next millennium? What will the editor ofthe Journal in December, AD 3000, write asour most significant accomplishment in thepast 1000 years? Please send me your thoughts,and I will list some of the most interestingones in a future issue.Happy holidays and a very happy newmillennium!OMISSIONIn the August/October issue we neglectedto credit the GA group photo (printed onthe cover and on page 161) to MurrayPaulson, Edmonton Centre.208JRASC December / décembre 2000

CorrespondenceCorrespondanceDear Sir,A LIFE OF VARIABLE STARSMy first contact with the Royal AstronomicalSociety of Canada was in 1952. It wasfortunate that a five-month lecture tourof North America was to commence inVancouver and then to continue to otherCanadian astronomical centres. I knewthat most of my audiences had forgottenmore astronomy than I knew. Professionalastronomers throughout Canada were allso helpful and encouraging that they gaveme the confidence for the U.S. tour. HelenHogg, Jack Heard, and many others freelygave helpful advice on the problems thatconcerned me. A very happy result waslife-long friendships.After service in the Royal New ZealandNavy, I settled on Rarotonga in the CookIslands at the end of World War II. ThereI established my observatory to continuemy observations of variable stars. I alsodreamt of establishing a professionalobservatory and of having astronomytaught at a New Zealand University. I hadno idea how I would bring this about, butBrad Wood of Pennsylvania had expressedinterest and hence this first lecture tour.I had established the Variable StarSection (V.S.S.) of the Astronomical Societyof New Zealand many years before. Thislater became the R.A.S.N.Z. Directing itsactivities was a part time job until October1969 when I retired as Astronomer-in-Charge of the Mt. John UniversityObservatory, Lake Tekapo, New Zealand.I had, by then, seen my dreams come trueafter heading the Site Selection Survey ofNew Zealand. Along the way I led the multinationalEclipse Expedition to the SouthPacific in 1965; helped establish the NationalCommittee for Astronomy in New Zealand,and being its Chairman for many years;got New Zealand to adhere to the IAU; andbecame New Zealand’s first official delegateto the IAU.Since I retired from Mt. JohnObservatory, my life has been devoted fulltime to directing the activities of the V.S.S.,R.A.S.N.Z. We now have a database ofaround three million observations ofsouthern variables and have taken part injust over 1,000 special programmes requestedby professionals worldwide. The only paidstaff we have is a part-time secretary. Ourwork is financed by subscriptions to ourcharts and other publications and by salesof Paradise Beckons. Grants have suppliedour computers.I have visited Canada on manyoccasions, especially when my elder daughterwas alive. I have visited several Canadianobservatories during these trips but havenot been able to be in the country duringthe annual meetings of your society. Mydaughter was a medical missionary inSaskatoon working with Metis and Indianpeople. This has given me a great love forCanada and its people, especially as I havebeen privileged to experience many facetsof life unknown even to many Canadians.Some of my grandchildren and greatgrandchildrenlive in various parts ofCanada, but my days of travel are over.Frank M. BatesonTauranga, New Zealand[Editor’s Note: Frank M. Bateson has beenan honourary member of the RASC sinceMarch 1984.]Dear Sir:MEDICINE WHEELSI read with great interest David A. Rodger’sletter in the April 2000 issue (JRASC, 94, 44,2000) responding to my article on medicinewheels. The facts he puts forth do challengethe theory of medicine wheels being activeobservatories and I, for one, would like tohave additional information. Progress isnot made by agreement, but by disagreement.Still, certain points should be made.Prehistoric peoples may not have neededsuch accuracy. If a hill stood in their wayand the Sun rose 30 minutes later than ourinstruments tell us, it may not have matteredto them. What was important was that itrose in a certain spot.There is the question of the sunburststone patterns, such as the one found atthe Minton Turtle Medicine Wheel, nearwhat could be a sunrise alignment. Werethese arrangements made for a set purpose?There still remains the question ofthe shapes of these wheels. Were theyaccidental or not? The similarity betweenthe medicine wheels and stone circles foundin Britain, a point raised by Mr. Rodger, ismost interesting. Another question concernsthe relationship of the main axis of a Creesundance lodge and possible sunrisealignments, as well as its similarity to theRoy Rivers medicine wheel.Questions and more questions, allserving to inspire the imagination and pushothers to seek the answers! These answersmay never be found, but seeking them willhelp to push outward the boundaries ofour knowledge concerning prehistoricsocieties. Mr. Rodger’s theories may becorrect. The medicine wheels may neverhave been used as observatories by thePlains Indians; however, until certainquestions can be answered, they may havebeen.In the meantime, I would be glad tohear from anyone who has information ortheories on the subject. I will be writingmore articles on prehistoric astronomy inthe future and perhaps some of thesequestions will be answered. Perhaps morequestions will be raised. Whatever happens,I am sure there will always be that whichcannot be known and that which will alwaysbe questioned.Barbara SilvermanSt. Laurent, QuébecDecember/ décembre 2000 JRASC209

News NotesEn ManchettesWEATHER FORECASTS FORCANADIAN ASTRONOMERSA sample cloud forecast image for westernCanada from the CMC web site. The originalimage uses colours to represent the highestand lowest clouds so some information is lostwhen converted to black and white. Imagecourtesy of Allan Rahill and CMC.During a night of deep sky observing orhigh precision photometry a thin veil ofcirrus cloud can often spoil the sky andruin a night’s observing. Yet the weatherforecast may have predicted clear skiesfor that night. For most people the skywould be clear enough, but for astronomersit is a disaster.For years the public forecast maynot have been specific enough to predictthis kind of situation. Now, Allan Rahillof the Canadian Meteorological Centre(CMC) in Dorval, Quebec has developeda 48-hour web forecast specifically forastronomers (www.cmc.ec.gc.ca/cmc/htmls/astro_e.html). Rahill’s productis based on work done by Arne Alfheim,also from CMC. Alfheim used the outputfrom the Canadian regional meteorologicalforecasting model to produce a simulatedsatellite image of the cloud cover. Theimage is fashioned after the 10.70-micronchannel from the Geostationary OperationalEnvironmental Satellites (GOES-8 andGOES-10). In these simulated infraredimages the higher, and thus colder cloudsshow up as brighter areas, while darkerareas indicate lower and warmer clouds.An animation loop shows the motion ofthe forecasted cloud deck and helps revealthe movement of low cloud, which caneasily be mistaken for terrain, especiallyin the colder months.Rahill is not only a meteorologistbut is also an avid amateur astronomerwith a robotic 0.56 metre Newtonian and30 years of observing experience, so heknows what astronomers want out oftheir weather forecasts. Eventually, hewould like to include actual transparencyand seeing values.These cloud cover forecasts comewith the same caveat as the regularforecasts. Since meteorologists can neverobtain perfect knowledge of the currentstate of the atmosphere, the forecastscan never be 100-percent accurate. Thefurther into the future the forecast looks,the less certain it becomes. Nonetheless,this new product should improveastronomers’ chances of finding clearskies.WHERE ARE EARTH’S TROJANS?How do you look for asteroids in Trojanorbits with the Earth? Well, for one thing,don’t look exactly in the place where youmight expect them to be. So writes Dr.Paul Wiegert, of the Department of Physicsand Astronomy at York University, andco-workers in a recent article publishedin the journal Icarus.Trojan asteroids occupy specialorbits. Their extraordinary nature stemsfrom the fact that they orbit the Sun atthe same distance as one of the planets,but they always remain either 60 degreesahead of, or behind, a line drawn betweenthe planet and the Sun. Joseph LouisLagrange first demonstrated the existenceof these special orbits, in which the asteroidremains stationary in the reference framerotating with the planet, in 1772. Indeed,Lagrange was able to show that withinthe so-called three-body gravitationalproblem five stable points should existin the reference frame rotating with theplanet. The Trojan orbits correspond toasteroids orbiting the Sun at the LagrangeL4 and L5 points, and they fall at theapexes of two equilateral triangles drawneither side of the planet–Sun line.The first Trojan object, asteroid 588Achilles, was discovered in 1906, and itresides at the L4 point of the Jupiter–Sunsystem. At the latest count, Jupiter hassome 466 Trojan companions, and theplanet Mars has two. In principle theEarth may have an accompanying troopof Trojan objects, but to date none havebeen discovered. This may be, as PaulWeigert, Kimmo Innanen and SeppoMikkola point out in their recentpublication, because the best searchstrategy for finding Earth Trojans is notnecessarily the one that simply monitorsthe region of the sky containing Earth’sL4 and L5 points.Weigert and co-workers highlighttwo important points in their study. Firstly,asteroids near the L4 and L5 points can,in fact, move on “tadpole-like” orbits,which enables them to temporarily moveahead of and behind the stable positions.This effect alone can widen the sky searcharea by several tens of degrees on eitherside of the Lagrange points. In addition,the brightness of an asteroid is not onlyrelated to its distance from Earth, butalso to its phase angle (the angle subtendedbetween the Earth, the asteroid, and theSun). By modeling both the brightnesseffect, and including “tadpole” orbits,Weigert et al. find that the best place tolook for, and detect, Earth Trojans arenot at the L4 and L5 points, but in regionsthat are displaced some five degrees closerto the Sun.After examining several hypothetical210JRASC December / décembre 2000

populations of Earth Trojan asteroids,Weigert and co-workers conclude thatwithin the limits set by previous surveys,there may well be a whole host of Earthaccompanying Trojans, and that some ofthem could conceivably be as large asseveral hundred metres.SOS (SAVING OSHAWA SKIES)Light pollution has been a growing urbanproblem for many years. So the occasionalvictory for the astronomer is all the moresweet, and indeed as recently announcedby Michael Cook, of the Toronto Centre,Oshawa City astronomers appear set foran improvement in their nighttime skies.Acting upon the recommendationsof a city review panel, Oshawa citycouncillors have recently agreed to adopta new lighting policy. The new policy willspecifically ensure that all new andreplacement streetlights will be of a fullcut-off (FCO) design. These lightingfixtures direct all their light downwardwith essentially no spillover to the sidesand, more importantly for astronomers,above. The city has also agreed to negotiatewith commercial and industrial developersto install FCO lighting as part of site plancontrol (prior to issuing new buildingpermits).Michael offers some sound advicefor other astronomers who might wantto approach their city councils aboutlighting policies. Firstly, he comments,focus on the energy waste and environmentprotection aspects. Secondly, get as manycouncillors as you can directly involvedwith the project, and take them on a tourof the city, demonstrating good and badlighting. After these first two steps, stickwith the process — you will have to contactcity staff, write letters, and make phonecalls. Finally, you will have to prepare aformal, but succinct, submission formunicipal consideration. The municipalclerk will have to be consulted with respectto placing the item on the council agenda.At this stage it would be a good idea toprepare a five to ten minute presentationon the issue of light pollution (and thebenefits of using FCO lighting) — youmight also be called upon to support thesubmission when Council eventually hearsit. The process takes time, but with a littleplanning and forethought, even citycouncils can be won over.Further details on the light pollutionproblem can be found in David Crawford’sarticle in The Observer’s Handbook. Theweb site of the International Dark-SkyAssociation can also be consulted atwww.darksky.org.MORE TAGISH LAKEMETEORITE SURPRISESThe Tagish Lake meteorite is one of akind. Well, at the very least, it appears tobe a new, intermediate type ofcarbonaceous chondrite. The strangecomposition of the Tagish Lake meteoritehas been the focus of two recent studies,both of which concluded that the meteoriteis a misfit with respect to the presentclassification scheme.Following its fall on January 18 th ,fragments of the Tagish Lake meteoritewere studied by Dr. Michael Lipschultzand his graduate student Jon Friedrichat Purdue University. Lipschultz andFriedrich performed a detailed study ofthe meteorite’s chemical make-up usinga plasma mass spectrometer, and theyfound that the meteorite was genuinelyunique, differing in several importantaspects from previously studiedcarbonaceous chondrites. Since thecarbonaceous chondrite meteorites arebelieved to be among the oldest and leastprocessed meteorites, the new findingsindicate that the Tagish Lake meteoritecontains material from a previouslyunsampled region of the solar nebula.The recent announcements byLipschultz and Friedrich complement anearlier electron microprobe study of theTagish Lake meteorite samples by Dr.Michael Zolensky, of NASA Johnson SpaceCenter, and co-workers. Presenting theirresults at the 63 rd Annual MeteoriticalSociety Meeting at the Fields Museum ofNatural History (held at the Universityof Chicago this past August) Zolenskyand co-workers commented that themeteorite was clearly “something new.”The Zolensky study specifically notes thatwhile the Tagish Lake meteorite hascharacteristics similar to those of the twoknown carbonaceous chondrite classes,the so-called CM and CI classes, it alsoindicates signs of extensive aqueousalteration, sulfidation, and oxidation.Further details and developmentsconcerning the Tagish Lake meteoritemay be found at a dedicated web pagelocated at phobos.astro.uwo.ca/~pbrown/tagish/.PRAIRIE METEORITE SEARCH –TWO UP!Wilfred Kunz and son Wayne display the newSaskatchewan meteorite find. The 3-kg chondritic(stony) meteorite was found this past May atDelaine Lake, near Annaheim. It is quite likelythat companion meteorites will reside in thesurrounding area.Saskatchewan and Alberta are now tiedas Canada’s leading provinces for meteoritefinds. The discovery of the 14 thSaskatchewan meteorite was recentlyannounced by the project leaders of thePrairie Meteorite Search, making it thesecond Saskatchewan find of the summerand the 55 th Canadian meteorite to beidentified.The new meteorite was actuallycollected this past May by Wilfred Kunzof Humbolt, Saskatchewan, while pickingrocks on his son’s farmstead. “I noticedwhen I picked it up that it was different— rusty and heavy with pockets on itssurface — though I didn’t think it was ameteorite at the time,” commented Kunz.That the “odd rock” was, in fact, a meteoritebecame clear this August after AndrewBird, a third-year geology student at theDecember/ décembre 2000 JRASC211

University of Calgary, hosted a PrairieMeteorite Search “Show and Tell” sessionat Watson Museum. Kunz took his newlyfoundrock along to the Museum andshowed it to Bird, who commented thathe “immediately suspected that the rockwas a meteorite.” Dr. Alan Hildebrand,of the University of Calgary, furthercommented that the ‘rock’ had “thecharacteristic texture of a weatheredmeteorite,” and that the meteorite probablyfell several thousand years ago.The new meteorite was found nearDelaine Lake in Central Saskatchewan,not far, in fact, from the town of Annaheim,where an iron meteorite was found in1914. That two totally different meteoritefinds have been made at locations just14.5 kilometres apart is a nice indicatorof just how thickly these extraterrestrialrocks lie upon the prairies.More details on the Prairie MeteoriteSearch can be found at its home page:www.geo.ucalgary.ca/PMSearch/.ADVERTISE IN THE JOURNALThe Journal now accepts commercial advertising. By advertising within these pages you willreach the over 4000 members of the RASC, who are the most active and dedicated amateurand professional astronomers in Canada. The Journal is also distributed by subscription touniversity libraries and professional observatories around the world.BLACK AND WHITE RATESSIZE One Insertion Three Insertions1/8 Page $125 $1151/6 Page $150 $1401/4 Page $175 $1601/2 Page $250 $225Full Page $375 $340Inside Back Cover $500 $425Outside Back Cover $750 $550For information or to receive a copy of our advertising flyer contact:RASC Journal AdvertisingPO Box 31011, Halifax, NS, B3K 5T9Telephone: 902-420-5633Fax: 902-826-7957E-Mail: ads@rasc.ca212JRASC December / décembre 2000

Feature ArticlesArticles de FondThe Space Surveillance Researchand Analysis Laboratoryby Michael A. Earl (earl-m@rmc.ca)introductionThe Space Surveillance Researchand Analysis Laboratory (SSRAL)at the Royal Military College (RMC)was founded in 1996 to establish an opticalsensor to be used specifically for highaltitude satellite tracking. The laboratorybegan its research into tracking Russiancommunications satellites in the summerof 1997 in order to study their uniqueorbits. This work spawned other researchinto the dynamics of satellites, such asdetermining satellite tumbling periodsand predicting orbit decay.The history of the SSRAL is a shortbut very interesting one. When thelaboratory began, it had virtually noequipment with which to track satellites.As the laboratory grew, it acquiredtechnologies that greatly increased itsdata output and data precision. Today,SSRAL has nearly completed theconstruction of its automatic satellitetracking facility, called The CanadianAutomated Small Telescope for OrbitalResearch (CASTOR).This is a brief description of thepast, present, and future of the SSRAL asviewed through the eyes of its seniortechnician, who has worked at the labfrom May 1997 to the present time.historyWhen I began working for the SSRAL, Idid not know anything about satellitetracking except that artificial satellitesorbited the Earth and that I could seesome of them crossing the sky at night.I was, however, a 20-yearveteran, so to speak, ofobservational backyardastronomy. In May 1997,the SSRAL had not yetassembled its officefurniture, which lay inboxes in one corner of thelab. It owned no telescopeswith which to tracksatellites. The only thingit did have was four Sunworkstations with satelliteorbit analysis software.My job was to learn howto use this software toanalyze data collected bythe University of Victoria (UVic). The goalat that time was to determine the orbitalcharacteristics of specific satellites.Very little data were actually collectedat UVic before the satellite-tracking projectthere ran out of funding and closed down.The SSRAL was then left in a quandary.The SSRAL still had no equipment toperform the data collection, but my own8-inch reflecting telescope was available.I decided to attempt to see a Molniyasatellite from the roof of the Sawyerbuilding at RMC using my own equipment.Molniya satellites are Russiancommunications satellites first launchedby the Soviet Union in 1965 to providetelevision, telephone, and telegraph servicesfor much of the Russian sub-continent.Molniya satellites’ orbits are inclined at63 degrees to the equatorial plane (theplane defined by the Earth’s equator).Their orbits are also highly eccentric. Asa result, the difference between the apogeeA typical Molniya satellite consists of a cylinder of 1.6-metrediameter and 3.4 metre length surrounded by six 5-metre solararrays. Its total mass is 1600 kg. There are currently 73 of thesesatellites in orbit. Fewer than 25 percent of the orbiting Molniyasatellites are still operational.(furthest distance from Earth) and perigee(closest distance to Earth) of the satellitesis substantial. At apogee the satellitescan reach an altitude (the height abovethe Earth’s surface) of about 40,000 kmwhile at perigee the altitude is a mere 400km. The high eccentricity of the orbitsensures that the satellites are well placedover Russia for a large portion of theirorbits. They generally stay over the NorthernHemisphere for about 10 hours of their12-hour total orbital period. Since theMolniya satellites orbit twice every 24hours, this means that at every secondorbit each satellite is over North Americaand not Russia. For those readers whoare wondering, some of the Molniyasatellites were indeed used as spy satellitesduring the Cold War.Molniya satellites have three distinctdesignations. The first series is namedMolniya 1-1, 1-2, etc, in order of launch.The most recent of these has been MolniyaDecember/ décembre 2000 JRASC213

The orbit of a typical Molniya satellite. Thehigh altitude at apogee ensures a long observingopportunity for satellite trackers in the NorthernHemisphere.1-91 which was launched September 28,1998. This series is primarily for governmentand military use.The second series of Molniya satellitesis named Molniya 2-1, 2-2, etc. This serieswas originally used for emergencycommunications between the U.S. andthe Soviet Union (the Hotline if you will).The last of these satellites (Molniya 2-17) was launched in February 1977, andthis series is no longer used. Only five ofthe original 17 launched (2-9, 2-10, 2-13,2-14, and 2-17) are still orbiting Earth.The rest have since fallen back to Earth.The third and final series is namedMolniya 3-1, 3-2, etc. These satellites areused for private companies (mainlytelevision and telephone). The most recentof these satellites (Molniya 3-50) waslaunched on July 8, 1999.In order for me to predict where aspecific Molniya satellite would be, it wasnecessary to use the satellite orbit analysissoftware that SSRAL had at the time. Itcould generate an ephemeris (a list oftimes and coordinates to find a specificobject) for an observer’s location, but itused only the alt-azimuth coordinatesystem (most common for Dobsoniantelescopes). The 8-inch aperture telescopethat I was using had a fork mount thatThis is one of the first photographs of a Molniyasatellite taken at the Royal Military College.Molniya 1-75 appeared to have a flash periodof about one minute. The small streaks madeby the satellite as it was orbiting the Earthare circled. This photo was taken at about06:30 UT on August 6, 1997. The telescopeused was a Criterion 8-inch Schmidt-Cassegrainreflecting telescope with a 35mm cameramounted at prime focus. The exposure timewas 5 minutes with Fuji 1600 ISO film. Thefield of view is 38 by 57 arcminutes.used equatorial coordinates, that is RightAscension (RA) and Declination (Dec).I wrote a program to do a coordinateconversion from alt-azimuth to equatorialcoordinates, and made predictions for afew Molniya satellites. On June 15, 1997,I successfully detected the satellite Molniya3-37 passing through my telescopic fieldof view. The satellite was about 17,000km from RMC at the time. Its brightnesswas about 9 th magnitude (about thebrightness of the planet Neptune). Idetected the satellite again five minuteslater to make sure I had indeed seen theright object. The Molniya satellite cannotbe confused with an airplane becauseMolniya satellites are so much furtheraway, so they appear to move much sloweracross the sky. My most memorable sightingof a Molniya satellite was Molniya 1-75on July 31, 1997. When I first glimpsedthis object, it appeared to be flashingbrightly once every minute. The satellitewas actually tumbling, and the brightflashes resulted from the reflection ofsunlight off its solar panels. The brightnessof the flashes was estimated to be 6 thmagnitude (about the brightness of theplanet Uranus). Because of the brightness,the color of the satellite could be seen asa brilliant yellow-gold. This satellite wasabout 40,000 km from RMC at the timeand could be seen only when the flashesoccurred. The light intensity when it wasnot flashing was fainter than 13 th magnitude(about the brightness of the planet Pluto)since it disappeared from detection byeye in an 8-inch telescope. A peculiaraspect of the sighting of this object wasthat it had entered the field of view a full1 1 ⁄2 minutes before the predicted time.The next day SSRAL investigated this anddiscovered that the orbital elements forthat particular satellite had not beenupdated since May 1997, a full two monthsearlier. (The orbital elements for a satelliteare not constant, since forces such as theMoon’s gravity, the solar wind, andatmospheric drag (friction) change theseelements daily.) Normally the orbitalelements are updated every day or two.In effect, the satellite had been lost forapproximately two months. SSRALimmediately contacted the U.S. SpaceCommand at Cheyenne Mountain,Colorado to report its sightings, and theorbital elements for Molniya 1-75 wereupdated the following day. The SSRALhad made a contribution by finding a lostsatellite with borrowed equipment.The next step was to obtain actualimages of a Molniya satellite in orbit. Iset up my 8-inch reflector and mountedmy 35mm camera at the telescope’s primefocus. My target was Molniya 1-75, thesatellite that exhibited bright flashes. Ihad never taken an image of a satellitebefore, at least not intentionally, so Idecided to use a fast (1600 ISO) film toimprove my chance of capturing an imageof the satellite. On August 6, 1997, SSRALobtained its first film images of the Molniya1-75 satellite. The flashing satellite waseasily seen within the test image.On August 19, 1997, Mr. Phil Somers(one of the founders of the SSRAL) andI set up two telescopes on the roof of theSawyer building for an all-night visualsatellite tracking session of the satelliteMolniya 1-75. This satellite had beenexhibiting 6 th magnitude flashes since itwas found by SSRAL. The aim was togather accurate data on the satellite’sposition. Star maps of the predictedpositions of the satellite at specific timeswere created. Whenever the satellite wasobserved to flash, its position was drawn214JRASC December / décembre 2000

on the appropriate star map, and the timewas recorded. This was done every fiveminutes for the entire night. Nearly 100observations of the satellite were madeduring this night.While these observations were beingcarried out, the satellite’s flashing becameunusual. Instead offlashing brightlyonce every minute,every alternate flashwas growing dimmeras the nightprogressed. At theend of the observingsession only everyalternate flash wasvisible. What thistold us was thatMolniya 1-75 hadnot been tumblingonce every minuteas we had believed,but every twominutes since wewere seeing twodifferent sides of thesatellite.The data were used to update theorbital elements of the satellite in orderto find it again. On September 4, 1997,film images of Molniya 1-75 were collected.From 03:54 to 05:02 UT I obtained twelvephotos of the satellite and analyzed theseimages using my own astrometry software.The data collected were used to updatethe orbital elements of the satellite.It was obvious to us that analyzingfilm images of the satellite streaks wasan impractical exercise and that a moreefficient means of imaging was needed.In January 1998, SSRAL had learned of aMeade 10-inch reflecting telescope andan SBIG ST-6 CCD (Charge Coupled Device)digital camera that were not being used.SSRAL decided to acquire this equipmentfrom the Astronomy Lab at RMC to begintracking Molniya satellites using CCDtechnology. Unlike my telescope, theMeade 10-inch was stepper-motor drivenand could be controlled via a telescopecontroller assembly. The 10-inch Meadealso had 1.6 times the light-gatheringcapability of my 8-inch telescope. Thismeant that dimmer objects (such assatellites with higher ranges) could bedetected. There were many advantagesto using a CCD camera instead of film.The major one was its superior sensitivity.Another advantage over film was thatCCD images did not cost money to develop.The Meade 10-inch Schmidt-Cassegrain reflecting telescope is seen withthe equipment used to control it. This was the primary satellite trackingsystem used by SSRAL until its more advanced system went online onJanuary 29, 2000.The first SSRAL satellite trackingapparatus that employed a CCD camerawas used forthe first timeon February 6,1998 to trackthe satelliteMolniya 3-10.By coincidence,that satellitealso exhibitedbrightflashes. Morepractical CCDimages of anotherMolniyasatellite (1-75)were takenthree days later.Atotal of 24images of thesatellite wereacquired foranalysis. During that tracking run, thesatellite’s range had decreased from 38,000km to 13,500 km as the satellite headedfor its perigee. After the initial CCD successwith Molniya 1-75, SSRAL began an analysisof how sensitive the CCD camera was byexamining other Molniya satellites overmany viewing conditions. During thatanalysis, SSRAL obtained many imagesof those Molniya satellites that exhibitedflashes with periods much smaller thanthat of Molniya 1-75. SSRAL began doinga tumble analysis of every Molniya satelliteit found that exhibited flashes. The mostnotable at that time was Molniya 3-43.This satellite had been accidentally imagedby SSRAL during routine tracking of theMolniya 1-87 satellite. On April 12, 1998an all-night tracking session of the satellitewas undertaken to provide the data forthe most accurate tumble analysis of thatsatellite to date. A total of 159 images ofthe satellite were gathered during thatnight, yielding a total of 450 individualflashes. Using the data collected from theimages, the tumble period for Molniya3-43 was found to be about 4.5 seconds.Tumbling satellites exhibit variedlight curves since different sides of thesatellite are being illuminated as it tumbles.This could confuse the observer intobelieving that the satellite is tumbling ata faster rate than it actually is. To date,Molniya 1-87 was being tracked on March 17, 1998 when another satelliteappeared in the field of view. Later analysis confirmed this object as Molniya3-43. It is extremely rare that two Molniya satellites are seen in the same 11by 14 arcminute field of view. Molniya 3-43 is the most analyzed satellite asfar as tumble period is concerned because of its easily seen flashes and smallflash time. This was a 20-second exposure using the Meade 10-inch reflectorand SBIG ST-6 CCD camera at prime focus.fourteen other Molniya satellites havebeen found to flash and therefore couldhave their tumble periods determined.Décember/ decembre 2000 JRASC215

Until January 2000 the Image Reduction and Analysis Facility (IRAF) was used by SSRAL to performthe necessary astrometry to determine the coordinates of the centre of the image and the satellitestreak end-points. The accuracy of the determined coordinates was within 2 arcseconds.The tumble periods range from as low as3.5 seconds (for Molniya 3-39) to over 2minutes (for Molniya 1-75).When analyzing an image, the SSRALtook a specific approach. First, the imagewas examined to make sure there was asatellite streak to analyze. If the imagecontained a satellite streak, the imagewas then loaded into the software packageImage Reduction and Analysis Facility(IRAF). IRAF determined the coordinatesof each end-point of the streak (calledastrometry). Any object that was not asatellite (such as a faint galaxy, asteroid,nebula, etc.) had astrometry performedon it as well. The Right Ascension andDeclination coordinates of the centre ofthe image were also determined in orderto construct an index of images taken ofthe sky. This index contains the coordinatesof the center of the image, the year, month,date and time of the exposure, and thename of the satellite(s) within the image.The image itself is stored in the SSRALimage archive. This process generally took3 minutes per image if only a satellitestreak was being analyzed. The maximumtime was about 10 minutes per image.The data extracted from the images wereused to update the orbital elements ofthe satellite. Molniya satellites were trackedregularly throughout 1998. At the beginningof 1999, the SSRAL began to upgrade itsfacility with remote control and automationin mind.The present:Canadian AutomatedSmall Telescope forOrbital Research(CASTOR)Before January 1999, the SSRAL had askeleton satellite tracking facility in thesense that it had the means to tracksatellites, but it did so impracticably.Steps were taken to upgrade the existingsystem during 1999. These steps includedacquiring a more sensitive CCD camera,a larger aperture telescope, andastronomical software that allowedtelescope automation.SSRAL obtained new astronomicalsoftware called TheSky, manufactured bySoftware Bisque. This software provideda virtual display of the objects in the skyover RMC, including Molniya satellites.It could also be used to control the Meade10-inch telescope. Instead of typing theequatorial coordinates of the object youwanted the telescope to slew to, all thatwas needed was a point and click ontothe object and then another click ontothe “slew” command.The trick was getting the softwareto communicate with the telescopecontroller. After one week’s worth of work,I finally succeeded. An image of a satellitecould be taken every two to three minutes,instead of every three to five minutes,which was previously required. The bulkof the time was the download time of theST-6 CCD camera (1.5 minutes).SSRAL received a new Celestron 14-inch Schmidt-Cassegrain optical tubeassembly in December 1998 and theApogee model AP-7 CCD camera in May1999. The new CCD camera could be usedright away since it could be attached tothe Meade 10-inch telescope withoutdifficulty. The new CCD camera had manyadvantages over the older ST-6. Oneadvantage was that the Apogee CCD chipwas larger (512 by 512 pixels). Anotheradvantage was that the Apogee AP-7camera had a maximum of 85% quantumefficiency over the wavelength regionfrom 600 nm to 800 nm. A final advantagewas that the download time was just 10seconds which was 1 ⁄9 the download timeThe Celestron 14-inch Schmidt-Cassegrainreflecting telescope and the Software BisqueParamount GT-1100 robotic mount are thoroughlytested in the SSRAL lab before being sent tothe new observatory dome for preliminarynight viewing trials. The Apogee AP-7 CCDcamera is shown at the prime focus of thetelescope.216JRASC December / décembre 2000

for the SBIG ST-6 CCD.The SBIG ST-6 CCD camera wasofficially retired on May 13, 1999 whenthe Apogee camera took its first imagesof the satellite Molniya 3-14. At that timethis satellite was undergoing slow orbitaldecay. SSRAL did get an image of thesatellite, but the satellite appeared in thefield of view of the camera a fullminute after the predicted time.This was expected since satellitesthat are decaying in their orbitshave rapidly changing orbitalelements. This is mainly due to theincreased atmospheric drag as thesatellite gets nearer the Earth. Theperiod of the orbit decreases steadilyas the decay progresses.A new name was needed forthe still unfinished satellite trackingfacility. The name had to suggesta Canadian identity in the spacesurveillance realm. I had drawnup several acronyms, but CASTORseemed to be the best overall.CASTOR made an excellentacronym (Canadian AutomatedSmall Telescope for OrbitalResearch), and it is French forbeaver, a Canadian symbol. Sincethe name is French, it alsoencompasses this bilingual nation.Castor is also a star in Gemini(Alpha Geminorum) and thereforesuggests the astronomical natureof the facility.The summer and fall of 1999was a busy time for the SSRAL andme especially because of theacquisition and testing of newequipment. The observatory domethat would eventually house thenew CASTOR facility had to be assembledand tested. The GT-1100 robotic mountand the Apogee AP-7 CCD camera hadto be tested in the lab before they couldbe used for serious satellite tracking.The construction of the 10.5-footdiameter observatory dome to house theCASTOR components was plannedthoroughly. Mr. Orest Koroluk and Mr.Steve Lockridge, both of RMC, plannedand carried out the dome’s construction.Thanks to their expertise the dome wasbuilt by October 1999. The telescope,robotic mount, and CCD camera were allbrought up to the newly constructeddome in November 1999. Followingpreliminary alignments, such as properbalancing and polar alignment of therobotic mount, and power installation,on December 8, 1999 the CASTOR sawThe senior technician of the SSRAL looks out from the shutter ofthe CASTOR observatory. The telescopes encircling the dome aresome of the many reflecting telescopes that RMC has in its possessionfor general purpose work such as open houses and undergraduateastronomy labs.first light when Polaris was viewed througha 26mm focal length eyepiece. Apreliminary polar alignment was performedusing Polaris so that the telescope couldbe used on other objects. The satelliteMolniya 1-32 was viewed through theeyepiece in order to test the trackingefficiency of the mount. The colour of thesatellite was easily detected as a goldenyellow, which is the colour of the solarpanels. The computer link to the roboticmount was tested that night by writinga script to tell the robotic mount to followthe satellite. The Software Bisque scriptingsoftware called Orchestrate allows theuser to automate many processes includingthe pointing of the scope itself. One nightlater, on December 9, 1999, images ofSaturn were taken with a 35mm cameraattached to the prime focus of the 14-inch telescope.The first CASTOR image of aMolniya satellite (Molniya 1-75)was obtained at 04:00 UT onDecember 10, 1999. The CCD cameradid not yet have a cable long enoughto reach the lab from the observatoryso the controlling computer hadto be brought up to the dome inorder to obtain CCD images. Today,the CASTOR facility can be totallycontrolled from within the lab itself.The facility will be automated assoon as automatic dome controlhardware is installed near the endof 2000. Regular satellite trackingruns are made whenever clear skiespresent themselves. Even in itspresent state the CASTOR facilityhas already been used for graduatethesis projects and provides accuratesatellite tracking data for dataanalysis in both Canada and theU.S. At present the timing accuracyof the CCD camera is 1 millisecond.Plans are being made to better thisaccuracy to 0.1 millisecond. Thepresent accuracy of the astrometryperformed on images is about 2arcseconds.Since there are many satellitesto track in a given night, it isnecessary to find some way ofautomating the scheduling processas well. Scheduling involves finding thosesatellites that are accessible to the facilityat a specific time and creating a scheduleto optimize tracking them. Obvious factorsfor a satellite schedule are the apparentangular velocity of the satellite, thebrightness (phase) of the satellite, andthe elevation of the satellite above thehorizon at different times. I have developedsatellite-scheduling software that readsthe ephemeris files generated by oursatellite orbit analysis software. TheDecember/ décembre 2000 JRASC217

scheduler automatically chooses theexposure time for the satellite based onits range from the facility and its elevationabove the horizon (for sight obliquity).This scheduler has been thoroughly tested,and it is now ready to be integrated intothe CASTOR system for future automation.The CASTOR project is currently inits research and development stage andthe first CASTOR facility in Kingston(CASTOR K) should be automated by thesummer of 2001.The FutureThe CASTOR K facility at RMC in Kingstonwill be the first of three CASTOR facilitieslocated in Canada. The second CASTORfacility (CASTOR S) will be located at theDefense Research Establishment Suffield(DRES) in southern Alberta. The thirdCASTOR facility (CASTOR V) has beenproposed for the Defense ResearchEstablishment Valcartier (DREV) insouthern Quebec. The purpose of havingthree facilities is twofold. First, the weatheris a major concern for optical telescopes.The probability of overcast skies at allthree facilities is smaller than that at onesingle facility. Second, satellite trackingdata obtained from more than one facilityis better than those obtained from a singleone, because data from two or morefacilities can be used for parallaxdeterminations of the satellite’s range.As a result, not only angle data are obtainedfrom the facilities, but range data as well.This improves the orbital determinationaccuracy and therefore will provide abetter ephemeris for finding the satelliteat a later time.These three facilities will be linkedvia a secure network to a single commandcentre located at the SSRAL. After thislink is established, the three facilities willbe used remotely from the commandcentre. Weather sensors at each site willprovide a synopsis of the respective facility’ssky conditions in real-time.Michael Earl is currently a senior technicianat the Space Surveillance Research andAnalysis Laboratory at the Royal MilitaryCollege, Kingston, Ontario. For the past threeyears, he has been responsible for the designand testing of various satellite trackingfacilities, including the Canadian AutomatedSmall Telescope for Orbital Research.Astronomy at RMCThe Royal Military College of Canadahas in its possession many astronomicaltelescopes for general purpose usessuch as open houses and undergraduateprojects. The Department of Physicsat RMC currently owns ten 5-inchreflecting telescopes, two 8-inchCelestron telescopes, and the 10-inchMeade Quartz telescope that wasoriginally used by the SSRAL for trackingsatellites.Plans are being made for at leastthree open houses to be held everysummer. These open houses are generallyfor the staff at RMC as well as RASCmembers. RMC also offers undergraduateand graduate degrees in Space Science.See the RMC web site for more details:www.rmc.ca.Visit the RASC Websitewww.rasc.caRASC INTERNET RESOURCESContact the National Officerasc@rasc.caJoin the RASC’s E-mail Discussion ListThe RASCals is a forum for discussion among members of the RASC. The forum encourages communication among members across the country andbeyond. It began in November 1995 and currently has about 265 members.To join the list, send an e-mail to listserv@ap.stmarys.ca with the words “subscribe rascals Your Name (Your Centre)” as the first line of themessage. For further information see: www.rasc.ca/computer/rasclist.htm218JRASC December / décembre 2000

Illustration by Brian G Segalby John N. BahcallWhat makes the sun shine? Howdoes the sun produce the vastamount of energy necessaryto support life on earth? These questionschallenged scientists for a hundred andfifty years, beginning in the middle of thenineteenth century. Theoretical physicistsbattled geologists and evolutionarybiologists in a heated controversy overwho had the correct answer.Why was there so much fuss aboutthis scientific puzzle? The nineteenthcenturyastronomer John HerschelSunshine makes life possible on earth.described eloquently the fundamentalrole of sunshine in all of human life inhis 1833 Treatise on Astronomy:The sun’s rays are the ultimatesource of almost every motionwhich takes place on the surfaceof the earth. By its heat areproduced all winds, ... By theirvivifying action vegetables areelaborated from inorganic matter,and become, in their turn, thesupport of animals and of man,and the sources of those greatdeposits of dynamical efficiencywhich are laid up for human usein our coal strata.In this essay, we shall review froman historical perspective the developmentof our understanding of how the sun (thenearest star) shines, beginning in thefollowing section with the nineteenthcenturycontroversy over the age of thesun. In later sections, we shall see howseemingly unrelated discoveries infundamental physics led to a theory ofnuclear energy generation in stars thatresolved the controversy over the age ofthe sun and explained the origin of solarradiation. In the section just before thesummary, we shall discuss how experimentsthat were designed to test the theory ofnuclear energy generation in stars revealeda new mystery, the Mystery of the MissingNeutrinos.I. The Age of the SunHow old is the sun? How does the sunshine? These questions are two sides ofthe same coin, as we shall see.The rate at which the sun is radiatingenergy is easily computed by using themeasured rate at which energy reachesthe earth’s surface and the distance betweenthe earth and the sun. The total energythat the sun has radiated away over itslifetime is approximately the product ofthe current rate at which energy is beingemitted, which is called the solar luminosity,times the age of the sun.The older the sun is, the greater thetotal amount of radiated solar energy.The greater the radiated energy, or thelarger the age of the sun, the more difficultit is to find an explanation of the sourceof solar energy.To better appreciate how difficultit is to find an explanation, let us considera specific illustration of the enormousrate at which the sun radiates energy.Suppose we put a cubic centimeter of iceoutside on a summer day in such a waythat all of the sunshine is absorbed bythe ice. Even at the great distance betweenthe earth and the sun, sunshine will meltthe ice cube in about 40 minutes. Sincethis would happen anywhere in space atthe earth’s distance from the sun, a hugespherical shell of ice centered on the sunand 300 million km (200 million miles)**Published with permission from Nobel e-Museum, http://www.nobel.se/, June 2000.December/ décembre 2000 JRASC219

in diameter would be melted at the sametime. Or, shrinking the same amount ofice down to the surface of the sun, wecan calculate that an area ten thousandtimes the area of the earth’s surface andabout half a kilometer (0.3 mile) thickwould also be melted in 40 minutes bythe energy pouring out of the sun.In this section, we shall discuss hownineteenth-century scientists tried todetermine the source of solar energy,using the solar age as a clue.A. Conflicting Estimatesof the Solar AgeThe energy source for solar radiation wasbelieved by nineteenth-century physiciststo be gravitation. In an influential lecturein 1854, Hermann von Helmholtz, aGerman professor of physiology whobecame a distinguished researcher andphysics professor, proposed that the originof the sun’s enormous radiated energy isthe gravitational contraction of a largemass. Somewhat earlier, in the 1840’s, J.R. Mayer (another German physician)and J. J. Waterson had also suggested thatthe origin of solar radiation is theconversion of gravitational energy intoheat. 1 Biologists and geologists consideredthe effects of solar radiation, while physicistsconcentrated on the origin of the radiatedenergy. In 1859, Charles Darwin, in thefirst edition of On The Origin of the Speciesby Means of Natural Selection, made acrude calculation of the age of the earthby estimating how long it would takeerosion occurring at the current observedrate to wash away the Weald, a great valleythat stretches between the North andSouth Downs across the south of England.He obtained a number for the “denudationof the Weald” in the range of 300 millionyears, apparently long enough for naturalselection to have produced the astoundingrange of species that exist on earth.As Herschel stressed, the sun’s heatis responsible for life and for most geologicalevolution on earth. Hence, Darwin’sestimate of a minimum age for geologicalactivity on the earth implied a minimumestimate for the amount of energy thatthe sun has radiated.Firmly opposed to Darwinian naturalselection, William Thompson, later LordKelvin, was a professor at the Universityof Glasgow and one of the great physicistsof the nineteenth century. In addition tohis many contributions to applied scienceand to engineering, Thompson formulatedthe second law of thermodynamics andset up the absolute temperature scale,which was subsequently named the Kelvinscale in his honour. The second law ofthermodynamics states that heat naturallyflows from a hotter to a colder body, notthe opposite. Thompson therefore realizedthat the sun and the earth must get colderunless there is an external energy sourceand that eventually the earth will becometoo cold to support life.Kelvin, like Helmholtz, was convincedthat the sun’s luminosity was producedby the conversion of gravitational energyinto heat. In an early (1854) version ofthis idea, Kelvin suggested that the sun’sheat might be produced continually bythe impact of meteors falling onto itssurface. Kelvin was forced by astronomicalevidence to modify his hypothesis andhe then argued that the primary sourceof the energy available to the sun was thegravitational energy of the primordialmeteors from which it was formed.Thus, with great authority andeloquence Lord Kelvin declared in 1862:That some form of the meteorictheory is certainly the true andcomplete explanation of solarheat can scarcely be doubted,when the following reasons areconsidered: (1) No other naturalexplanation, except by chemicalaction, can be conceived. (2) Thechemical theory is quiteinsufficient, because the mostenergetic chemical action weknow, taking place betweensubstances amounting to thewhole sun’s mass, would onlygenerate about 3,000 years’ heat.(3) There is no difficulty inaccounting for 20,000,000 years’heat by the meteoric theory.Kelvin continued by attackingDarwin’s estimate directly, askingrhetorically:What then are we to think ofsuch geological estimates as[Darwin’s] 300,000,000 years forthe “denudation of the Weald”?Believing Darwin was wrong in hisestimate of the age of the earth, Kelvinalso believed that Darwin was wrongabout the time available for naturalselection to operate.Lord Kelvin estimated the lifetimeof the sun, and by implication the earth,as follows. He calculated the gravitationalenergy of an object with a mass equal tothe sun’s mass and a radius equal to thesun’s radius and divided the result by therate at which the sun radiates away energy.This calculation yielded a lifetime of only30 million years. The correspondingestimate for the lifetime sustainable bychemical energy was much smaller becausechemical processes release very littleenergy.B. Who was Right?As we have just seen, in the nineteenthcentury you could get very differentestimates for the age of the sun, dependingupon whom you asked. Prominenttheoretical physicists argued, based uponthe sources of energy that were knownat that time, that the sun was at most afew tens of millions years old. Manygeologists and biologists concluded that1 von Helmholtz and Mayer were two of the codiscoverers of the law of conservation of energy. This law states that energy can be transformed from one formto another but the total amount is always conserved. Conservation of energy is a basic principle of modern physics that is used in analyzing the very smallest(sub-atomic) domains and the largest known structure (the universe) and just about everything in between. We shall see later that Einstein’s generalizationof the law of conservation of energy was a key ingredient in understanding the origin of solar radiation. The application of conservation of energy to radioactivityrevealed the existence of neutrinos.220JRASC December / décembre 2000

the sun must have been shining for atleast several hundreds of millions of yearsin order to account for geological changesand the evolution of living things, bothof which depend critically upon energyfrom the sun. Thus the age of the sun,and the origin of solar energy, wereimportant questions not only for physicsand astronomy, but also for geology andbiology.Darwin was so shaken by the powerof Kelvin’s analysis and by the authorityof his theoretical expertise that in thelast editions of On The Origin of Specieshe eliminated all mention of specific timescales. He wrote in 1869 to Alfred RusselWallace, the codiscoverer of naturalselection, complaining about Lord Kelvin:Thompson’s views on the recentage of the world have been forsome time one of my soresttroubles.Today we know that Lord Kelvin waswrong and the geologists and evolutionarybiologists were right. Radioactive datingof meteorites shows that the sun is 4.6billion years old.What was wrong with Kelvin’sanalysis? An analogy may help. Supposea friend observed you using your computerand tried to figure out how long thecomputer had been operating. A plausibleestimate might be no more than a fewhours, since that is the maximum lengthof time over which a battery could supplythe required amount of power. The flawin this analysis is the assumption thatyour computer is necessarily powered bya battery. The estimate of a few hourscould be wrong if your computer wereoperated from an electrical power outletin the wall. The assumption that a batterysupplies the power for your computer isanalogous to Lord Kelvin’s assumptionthat gravitational energy powers the sun.Since nineteenth century theoreticalphysicists did not know about thepossibility of transforming nuclear massinto energy, they calculated a maximumage for the sun that was too short.Nevertheless, Kelvin and his colleaguesmade a lasting contribution to the sciencesof astronomy, geology, and biology byinsisting on the principle that validinferences in all fields of research mustbe consistent with the fundamental lawsof physics.We will now discuss some of thelandmark developments in theunderstanding of how nuclear mass isused as the fuel for stars.II. A Glimpse ofthe SolutionThe turning point in the battle betweentheoretical physicists and empiricalgeologists and biologists occurred in 1896.In the course of an experiment designedto study x-rays, discovered the previousyear by Wilhelm Röntgen, Henri Becquerelstored some uranium-covered plates ina desk drawer next to photographic plateswrapped in dark paper. Because it wascloudy in Paris for a couple of days,Becquerel was not able to “energize” hisphotographic plates by exposing themto sunlight as he had intended. Ondeveloping the photographic plates, hefound to his surprise strong images ofhis uranium crystals. He had discoverednatural radioactivity, due to nucleartransformations of uranium.The significance of Becquerel’sdiscovery became apparent in 1903, whenPierre Curie and his young assistant,Albert Laborde, announced that radiumsalts constantly release heat. The mostextraordinary aspect of this new discoverywas that radium radiated heat withoutcooling down to the temperature of itssurroundings. The radiation from radiumrevealed a previously unknown source ofenergy. William Wilson and George Darwinalmost immediately proposed thatradioactivity might be the source of thesun’s radiated energy.The young prince of experimentalphysics, Ernest Rutherford, then a professorof physics at McGill University in Montreal,discovered the enormous energy releasedby alpha particle radiation from radioactivesubstances. In 1904, he announced:The discovery of the radio-activeelements, which in theirdisintegration liberate enormousamounts of energy, thus increasesthe possible limit of the durationof life on this planet, and allowsthe time claimed by the geologistand biologist for the process ofevolution.The discovery of radioactivity openedup the possibility that nuclear energymight be the origin of solar radiation.This development freed theorists fromrelying in their calculations on gravitationalenergy. However, subsequent astronomicalobservations showed that the sun doesnot contain a lot of radioactive materials,but instead is mostly hydrogen in gaseousform. Moreover, the rate at whichradioactivity delivers energy does notdepend on the stellar temperature, whileobservations of stars suggested that theamount of energy radiated by a star doesdepend sensitively upon the star’s interiortemperature. Something other thanradioactivity is required to release nuclearenergy within a star.In the next sections, we shall tracethe steps that led to what we now believeis the correct understanding of how starsshine.III. The DirectionEstablishedThe next fundamental advance cameonce again from an unexpected direction.In 1905, Albert Einstein derived his famousAston showed in 1920 that four hydrogennuclei are heavier than a helium nucleus.Décember/ decembre 2000 JRASC221

elation between mass and energy,E = mc 2 , as a consequence of the specialtheory of relativity. Einstein’s equationshowed that a tiny amount of mass could,in principle, be converted into a tremendousamount of energy. His relation generalizedand extended the nineteenth century lawof conservation of energy of von Helmholtzand Mayer to include the conversion ofmass into energy.What was the connection betweenEinstein’s equation and the energy sourceof the sun? The answer was not obvious.Astronomers did their part by definingthe constraints that observations of starsimposed on possible explanations ofstellar energy generation. In 1919, HenryNorris Russell, the leading theoreticalastronomer in the United States,summarized in a concise form theastronomical hints on the nature of thestellar energy source. Russell stressedthat the most important clue was thehigh temperature in the interiors of stars.F. W. Aston discovered in 1920 thekey experimental element in the puzzle.He made precise measurements of themasses of many different atoms, amongthem hydrogen and helium. Aston foundthat four hydrogen nuclei were heavierthan a helium nucleus. This was not theprincipal goal of the experiments heperformed, which were motivated in largepart by looking for isotopes of neon.The importance of Aston’smeasurements was immediately recognizedby Sir Arthur Eddington, the brilliantEnglish astrophysicist. Eddington arguedin his 1920 presidential address to theBritish Association for the Advancementof Science that Aston’s measurement ofthe mass difference between hydrogenand helium meant that the sun couldshine by converting hydrogen atoms tohelium. This burning of hydrogen intohelium would (according to Einstein’srelation between mass and energy) releaseabout 0.7% of the mass equivalent of theenergy. In principle, this could allow thesun to shine for about a 100 billion years.In a frighteningly prescient insight,Eddington went on to remark about theconnection between stellar energygeneration and the future of humanity:If, indeed, the sub-atomic energyin the stars is being freely usedto maintain their great furnaces,it seems to bring a little nearerto fulfillment our dream ofcontrolling this latent power forthe well-being of the human race— or for its suicide.IV. Understandingthe ProcessThe next major step in understandinghow stars produce energy from nuclearburning resulted from applying quantummechanics to the explanation of nuclearradioactivity. This application was madewithout any reference to what happensin stars. According to classical physics,two particles with the same sign of electricalcharge will repel each other, as if theywere repulsed by a mutual recognitionof “bad breath.” Classically, the probabilitythat two positively charged particles getvery close together is zero. But somethings that cannot happen in classicalphysics can occur in the real world whichis described on a microscopic scale byquantum mechanics.In 1928, George Gamow, the greatRussian-American theoretical physicist,derived a quantum-mechanical formulathat gave a non-zero probability of twocharged particles overcoming their mutualelectrostatic repulsion and coming veryclose together. This quantum mechanicalprobability is now universally known asthe “Gamow factor.” It is widely used toexplain the measured rates of certainradioactive decays.In the decade that followed Gamow’sepochal work, Atkinson and Houtermansand later Gamow and Teller used theGamow factor to derive the rate at whichnuclear reactions would proceed at thehigh temperatures believed to exist inthe interiors of stars. The Gamow factorwas needed in order to estimate how oftentwo nuclei with the same sign of electricalcharge would get close enough togetherto fuse and thereby generate energyaccording to Einstein’s relation betweenexcess mass and energy release.In 1938, C. F. von Weizsäcker cameclose to solving the problem of how somestars shine. He discovered a nuclear cycle,now known as the carbon-nitrogen-oxygen(CNO) cycle, in which hydrogen nucleicould be burned using carbon as a catalyst.However, von Weizsäcker did notinvestigate the rate at which energy wouldbe produced in a star by the CNO cycle,nor did he study the crucial dependenceupon stellar temperature.By April 1938, it was almost as if thescientific stage had been intentionallyset for the entry of Hans Bethe, theacknowledged master of nuclear physics.Professor Bethe had just completed aclassic set of three papers in which hereviewed and analyzed all that was thenknown about nuclear physics. These workswere known among his colleagues as“Bethe’s bible.” Gamow assembled a smallconference of physicists and astrophysicistsin Washington, D. C. to discuss the stateof knowledge, and the unsolved problems,concerning the internal constitution ofthe stars.In the course of the next six monthsor so, Bethe worked out the basic nuclearprocesses by which hydrogen is burned(fused) into helium in stellar interiors.Hydrogen is the most abundant constituentof the sun and similar stars, and indeedthe most abundant element in the universe.Bethe described the results of hiscalculations in a paper entitled “EnergyProduction in Stars,” which is awesometo read. He authoritatively analyzed thedifferent possibilities for reactions thatburn nuclei and selected as most importantthe two processes that we now believeare responsible for sunshine. One process,the so-called p – p chain, builds heliumout of hydrogen and is the dominantenergy source in stars like the sun andless massive stars.The CNO cycle, the second processwhich was also considered by vonWeizsäcker, is most important in starsthat are more massive than the sun. Betheused his results to estimate the centraltemperature of the sun and obtained avalue that is within 20% of what wecurrently believe is the correct value (16million degrees Kelvin) 2 . Moreover, heshowed that his calculations led to a222JRASC December / décembre 2000

elation between stellar mass and stellarluminosity that was in satisfactoryagreement with the available astronomicalobservations.In the first two decades after theend of the second world war, manyimportant details were added to Bethe’stheory of nuclear burning in stars.Distinguished physicists and astrophysicists,especially A. G. W. Cameron,W. A. Fowler, F. Hoyle, E. E. Salpeter, M.Schwarzschild, and their experimentalcolleagues, returned eagerly to the questionof how stars like the sun generate energy.From Bethe’s work, the answer was knownin principle: the sun produces the energyit radiates by burning hydrogen. Accordingto this theory, the solar interior is a sortof controlled thermonuclear bomb on agiant scale 3 . The theory leads to thesuccessful calculation of the observedluminosities of stars similar to the sunand provides the basis for our currentunderstanding of how stars shine andevolve over time. The idea that nuclearfusion powers stars is one of thecornerstones of modern astronomy andis used routinely by scientists in interpretingobservations of stars and galaxies.W. A. Fowler, Willy as he wasuniversally known, led a team of colleaguesin his Caltech Kellogg Laboratory andinspired physicists throughout the worldto measure or calculate the most importantdetails of the p – p chain and the CNOcycle. There was plenty of work to do,and the experiments and the calculationswere difficult. But the work got donebecause understanding the specifics ofsolar energy generation was so interesting.Most of the efforts of Fowler and hiscolleagues M. Burbidge, G. R. Burbidge,F. Hoyle, and A. G. W. Cameron) soonshifted to the problem of how the heavyelements, which are necessary for life,are produced in stars.V. Testing theHypothesis ofNuclear BurningScience progresses as a result of the clashbetween theory and experiment, betweenspeculation and measurement. Eddington,in the same lecture in which he firstdiscussed the burning of hydrogen nucleiin stars, remarked:I suppose that the appliedmathematician whose theoryhas just passed one still morestringent test by observationought not to feel satisfaction,but rather disappointment—“Foiled again! This time I hadhoped to find a discordance whichwould throw light on the pointswhere my model could beimproved.”Is there any way to test the theorythat the sun shines because very deep inits interior hydrogen is burned into helium?At first thought, it would seem impossibleto make a direct test of the nuclear burninghypothesis. Light takes about ten millionyears to leak out from the center of the sunto the surface and when it finally emergesin the outermost regions, light mainly tellsus about the conditions in those outerregions. Nevertheless, there is a way of“seeing” into the solar interior with neutrinos,exotic particles discovered while trying tounderstand a different mystery 4 .A. Discovery, Confirmation,and SurpriseA neutrino is a sub-atomic particle thatinteracts weakly with matter and travelsat a speed that is essentially the speed oflight. Neutrinos are produced in starswhen hydrogen nuclei are burned tohelium nuclei; neutrinos are also producedon earth in particle accelerators, in nuclearreactors, and in natural radioactivity.Based upon the work of Hans Bethe andhis colleagues, we believe that the processby which stars like the sun generate energycan be symbolized by the relation,4 1 H → 4 He + 2e + + 2v e + energy (1)in which four hydrogen nuclei ( 1 H, protons)are burned into a single helium nucleus( 4 He, particle) plus two positive electrons(e + ) and two neutrinos (v e ) plus energy.This process releases energy to the starsince, as Aston showed, four hydrogenatoms are heavier than one helium atom.The same set of nuclear reactions thatsupply the energy of the sun’s radiationalso produce neutrinos that can be searchedfor in the laboratory.Because of their weak interactions,neutrinos are difficult to detect. Howdifficult? A solar neutrino passing throughthe entire earth has less than one chancein a thousand billion of being stoppedby terrestrial matter. According tostandard theory, about a hundred billionsolar neutrinos pass through yourthumbnail every second and you don’tnotice them. Neutrinos can travelunaffected through iron as far as lightcan travel in a hundred years throughempty space.2According to the modern theory of stellar evolution, the sun is heated to the enormous temperatures at which nuclear fusion can occur by gravitationalenergy released as the solar mass contracts from an initially large gas cloud. Thus, Kelvin and other nineteenth-century physicists were partially right; therelease of gravitational energy ignited nuclear energy generation in the sun.3The sensitive dependence of the Gamow factor upon the relative energy of the two charged particles is, we now understand, what provides the temperature“thermostat” for stars.4The existence of neutrinos was first proposed by Wolfgang Pauli in a 1930 letter to his physics colleagues as a “desperate way out” of the apparent nonconservationof energy in certain radioactive decays (called β-decays) in which electrons were emitted. According to Pauli’s hypothesis, which he put forwardvery hesitantly, neutrinos are elusive particles which escape with the missing energy in β-decays. The mathematical theory of β-decay was formulated byEnrico Fermi in 1934 in a paper which was rejected by the journal Nature because “it contained speculations too remote from reality to be of interest to thereader.” Neutrinos from a nuclear reactor were first detected by Clyde Cowan and Fred Reines in 1956.December/ décembre 2000 JRASC223

This figure is a cross section of the sun. The features that are usually studied by astronomers withnormal telescopes that detect light are labeled on the outside, e. g., sunspot and prominences.Neutrinos enable us to look deep inside the sun, into the solar core where nuclear burning occurs.In 1964, Raymond Davis Jr. and Iproposed that an experiment with 100,000gallons of cleaning fluid (perchloroethylene,which is mostly composed of chlorine)could provide a critical test of the ideathat nuclear fusion reactions are theultimate source of solar radiation. Weargued that, if our understanding ofnuclear processes in the interior of thesun was correct, then solar neutrinoswould be captured at a rate Davis couldmeasure with a large tank filled withcleaning fluid. When neutrinos interactwith chlorine, they occasionally producea radioactive isotope of argon. Davis hadshown previously that he could extracttiny amounts of neutrino-produced argonfrom large quantities of perchloroethylene.To do the solar neutrino experiment, hehad to be spectacularly clever sinceaccording to my calculations, only a fewatoms would be produced per week in ahuge Olympic-sized swimming pool ofcleaning fluid.Our sole motivation for urging thisexperiment was to use neutrinos to:enable us to see into the interiorof a star and thus verify directlythe hypothesis of nuclear energygeneration in stars.As we shall see, Davis and I did notanticipate some of the most interestingaspects of this proposal.Davis performed the experiment,and in 1968 announced the first results.He measured fewer neutrinos than Ipredicted. As the experiment and thetheory were refined, the disagreementappeared more robust. Scientists rejoicedthat solar neutrinos were detected butworried why there were fewer neutrinosthan predicted.What was wrong? Was ourunderstanding of how the sun shinesincorrect? Had I made an error incalculating the rate at which solar neutrinoswould be captured in Davis’s tank? Wasthe experiment wrong? Or did somethinghappen to the neutrinos after they werecreated in the sun?Over the next twenty years, manydifferent possibilities were examined byhundreds, and perhaps thousands, ofphysicists, chemists, and astronomers 5 .Both the experiment and the theoreticalcalculation appeared to be correct.Once again experiment rescued purethought. In 1986, Japanese physicists ledby Masatoshi Koshiba and Yoji Totsuka,together with their American colleagues,Eugene Beier and Alfred Mann,reinstrumented a huge tank of waterdesigned to measure the stability of matter.The experimentalists increased thesensitivity of their detector so that it couldalso serve as a large undergroundobservatory of solar neutrinos. Their goalwas to explore the reason for thequantitative disagreement between thepredicted and the measured rates in thechlorine experiment.The new experiment (calledKamiokande) in the Japanese Alps alsodetected solar neutrinos. Moreover, theKamiokande experiment confirmed thatthe neutrino rate was less than predictedby standard physics and standard modelsof the sun and demonstrated that thedetected neutrinos came from the sun.Subsequently, experiments in Russia(called SAGE, led by V. Gavrin), in Italy(GALLEX and later GNO led by T. Kirstenand E. Belotti, respectively), and againin Japan (Super-Kamiokande, led by Y.Totsuka and Y. Suzuki), each with differentcharacteristics, all observed neutrinosfrom the solar interior. In each detector,the number of neutrinos observed wassomewhat lower than standard theorypredicted.What do all of these experimentalresults mean?Neutrinos produced in the centerof the sun have been detected in fiveexperiments. Their detection shows directlythat the source of the energy that the sunradiates is the fusion of hydrogen nucleiin the solar interior. The nineteenth centurydebate between theoretical physicists,geologists, and biologists has been settledempirically.From an astrophysical perspective,the agreement between neutrinoobservations and theory is good. Theobserved energies of the solar neutrinosmatch the values predicted by theory.The rates at which neutrinos are detectedare less than predicted but not by a large5Perhaps the most imaginative proposal was made by Stephen Hawking, who suggested that the central region of the sun might contain a small black hole andthat this could be the reason why the number of neutrinos observed is less than the predicted number.224JRASC December / décembre 2000

factor. The predicted neutrino arrival rateat the earth depends approximately uponthe 25 th power of the central temperatureof the sun, T × T ×...T (25 factors of thetemperature T). The agreement that hasbeen achieved (agreement within a factorof three) shows that we have empiricallymeasured the central temperature of thesun to an accuracy of a few percent.Incidentally, if someone had told me in1964 that the number of neutrinos observedfrom the sun would be within a factor ofthree of the predicted value, I would havebeen astonished and delighted.In fact, the agreement betweennormal astronomical observations (usinglight rather than neutrinos) and theoreticalcalculations of solar characteristics ismuch more precise. Studies of the internalstructure of the sun using the solarequivalent of terrestrial seismology (i.e.,observations of solar vibrations) showthat the predictions of the standard solarmodel for the temperatures in the centralregions of the sun are consistent with theobservations to an accuracy of at least0.1%. In this standard model, the currentage of the sun is five billion years, whichis consistent with the minimum estimateof the sun’s age made by nineteenthcenturygeologists and biologists (a fewhundred million years).Given that the theoretical modelsof the sun describe astronomicalobservations accurately, what can explainthe disagreement by a factor of two orthree between the measured and thepredicted solar neutrino rates?B. New PhysicsPhysicists and astronomers were onceagain forced to reexamine their theories.This time, the discrepancy was not betweendifferent estimates of the sun’s age, butrather between predictions based upona widely accepted theory and directmeasurements of particles produced bynuclear burning in the sun’s interior. Thissituation was sometimes referred to asthe Mystery of the Missing Neutrinos or,in language that sounded more scientific,the Solar Neutrino Problem.As early as 1969, two scientistsworking in Russia, Bruno Pontecorvo andVladimir Gribov, proposed that thediscrepancy between standard theoryand the first solar neutrino experimentcould be due to an inadequacy in thetextbook description of particle physics,rather than in the standard solar model.(Incidentally, Pontecorvo was the firstperson to propose using a chlorine detectorto study neutrinos.) Gribov and Pontecorvosuggested that neutrinos suffer from amultiple personality disorder, that theyoscillate back and forth between differentstates or types.According to the suggestion of Gribovand Pontecorvo, neutrinos are producedin the sun in a mixture of individual states,a sort of split personality. The individualstates have different small masses, ratherthan the zero masses attributed to themby standard particle theory. As they travelto the earth from the sun, neutrinososcillate between the easier-to-detectneutrino state and the more difficult-todetectneutrino state. The chlorineexperiment only detects neutrinos in theeasier-to-observe state. If many of theneutrinos arrive at earth in the state thatis difficult to observe, then they are notcounted. It is as if some or many of theneutrinos have vanished, which can explainthe apparent mystery of the missingneutrinos.Building upon this idea, LincolnWolfenstein in 1978 and Stanislav Mikheyevand Alexei Smirnov in 1985 showed thatthe effects of matter on neutrinos movingthrough the sun might increase theoscillation probability of the neutrinosif Nature has chosen to give them massesin a particular range.Neutrinos are also produced by thecollisions of cosmic ray particles with otherparticles in the earth’s atmosphere. In 1998,the Super-Kamiokande team ofexperimentalists announced that they hadobserved oscillations among atmosphericneutrinos. This finding provided indirectsupport for the theoretical suggestion thatsolar neutrinos oscillate among differentstates. Many scientists working in the fieldof solar neutrinos believe that, in retrospect,we have had evidence for oscillations ofsolar neutrinos since 1968.But we do not yet know what causesthe multiple personality disorder of solarneutrinos. The answer to this questionmay provide a clue to physics beyond thecurrent standard models of sub-atomicparticles. Does the change of identityoccur while the neutrinos are travelingto the earth from the sun, as originallyproposed by Gribov and Pontecorvo? Ordoes matter cause solar neutrinos to “flipout”? Experiments are underway in Canada,Italy (three experiments), Japan (twoexperiments), Russia, and the UnitedStates that are attempting to determinethe cause of the oscillations of solarneutrinos, by finding out how much theyweigh and how they transform from onetype to another. Non-zero neutrino massesmay provide a clue to a still undiscoveredrealm of physical theory.VI. Nature: AWonderful MysteryNature has written a wonderful mystery.The plot continually changes, and themost important clues come from seeminglyunrelated investigations. These suddenand drastic changes of scientific sceneappear to be Nature’s way of revealing theunity of all fundamental science.The mystery began in the middle ofthe nineteenth century with the puzzle:How does the sun shine? Almostimmediately, the plot switched to questionsabout how fast natural selection occursand at what rate geological formationsare created. The best theoretical physicsof the nineteenth century gave the wronganswer to all these questions. The firsthint of the correct answer came, at thevery end of the nineteenth century, fromthe discovery of radioactivity withaccidentally darkened photographic plates.The right direction in which to searchfor the detailed solution was revealed bythe 1905 discovery of the special theoryof relativity, by the 1920 measurement ofthe nuclear masses of hydrogen andhelium, and by the 1928 quantummechanical explanation of how chargedparticles get close to each other. Thesecrucial investigations were not directlyrelated to the study of stars.December/ décembre 2000 JRASC225

By the middle of the twentiethcentury, nuclear physicists andastrophysicists could calculate theoreticallythe rate of nuclear burning in the interiorsof stars like the sun. But, just when wethought we had Nature figured out,experiments showed that fewer solarneutrinos were observed at earth thanwere predicted by the standard theory ofhow stars shine and how sub-atomicparticles behave.At the beginning of the twenty-firstcentury, we have learned that solarneutrinos tell us not only about the interiorof the sun, but also something about thenature of neutrinos. No one knows whatsurprises will be revealed by the new solarneutrino experiments that are currentlyunderway or are planned. The richnessand the humor with which Nature haswritten her mystery, in an internationallanguage that can be read by curiouspeople of all nations, is beautiful, awesome,and humbling.ReferencesF. W. Aston, “The Mass-Spectra ofChemical Elements,” PhilosophicalMagazine and Journal of Science, 69,611-625 (1920). In the course of asystematic program to measure themasses of atoms, Aston found thatfour hydrogen nuclei (protons) areheavier than a helium nucleus (an alphaparticle) and two positive electrons[see Eq. (1)]. This fundamental discoveryis the experimental basis of ourunderstanding of how stars like thesun shine. The original paper is rarelycited, perhaps because the text is mainlydevoted to a description of Aston’s newapparatus and to a discussion of themany different masses that he measured.The hydrogen-helium mass differenceis only briefly mentioned.R. D. E. Atkinson and F. G. Houtermans,“Zur Frage der Aufbaumöglichkeit derElements in Sternen,” Z. Physik 54, 656(1929). An early attempt to calculatethe rate of nuclear reactions in starsusing the Gamow factor.J. N. Bahcall, “Solar Neutrinos I. Theoretical,”Phys. Rev. Lett. 12, 300 (1964).H. A. Bethe, “Energy production in Stars,”Phys. Rev. 55, 436 (1939). If you are aphysicist and only have time to readone paper in the subject, this is thepaper to read.J. D. Burchfield, Lord Kelvin and The Ageof the Earth, (Chicago: University ofChicago Press), 1990. This concise bookprovides a clear and insightful accountof Kelvin’s views on the age of the earthand the age of the sun, and on manyother topics including natural selectionand geological evolution. The authortells an exciting story with historicalaccuracy.C. L. Cowan Jr., F. Reines, F. B. Harrison,H. W. Kruse, and A. D. McGuire,“Detection of the Free Neutrino: aConfirmation”, Science 124, 103 (1956);F. Reines and C. L. Cowan, “Detectionof the Free Neutrino”, Phys. Rev. 92,830 (1953). These papers describe thefirst experimental detection of neutrinos.C. Darwin, On the Origin of Species byMeans of Natural Selection, or, ThePreservation of Favored Races in theStruggle for Life (London: Murray 1859),p. 285 [Pelican Preprint of first edition,296—297, 1968].R. Davis Jr., “Solar Neutrinos. II.Experimental,” Phys. Rev. Lett. 12, 302(1964).J. N. Bahcall and R. Davis Jr., “An Accountof the Development of the Solar NeutrinoProblem,” in Essays in NuclearAstrophysics, ed. C. A. Barnes, D. D.Clayton, and D. Schramm (Cambridge:Cambridge University Press 1982), p.243; reprinted in J. N. Bahcall, NeutrinoAstrophysics, (Cambridge: CambridgeUniversity Press 1989). For relatedmaterial, see http://www.sns.ias.edu/~jnb/Papers/Popular/snhistory.html.A. S. Eddington, “The Internal Constitutionof the Stars,” Observatory 43, 353 (1920).This lecture is inspiring.A. Einstein, “Zur Elektrodynamik bewegterKörper,” Annalen der Physik, 17 (105).English translation in The Principle ofRelativity, translated by W. Perrett andG. B. Jeffery with notes by A. Sommerfeld,(Dover Publications: New York), 1923.The logic in this paper is breathtakinglybeautiful and incredibly clear.E. Fermi, “Tentativo di una teoria dellaemissione di raggi ?” Ric. 4, 491 (1934).Reprinted in Enrico Fermi, CollectedPapers: Note e memorie, Vol 1. p. 538(University of Chicago Press: Chicago)(1962-1965). See also pp. 559, 575. Fermiformulated the mathematical theoryof neutrino emission in β-decay. Hisfirst paper on the subject was rejectedas “too speculative” for publication.W. A. Fowler, “Experimental and theoreticalnuclear astrophysics: the quest for theorigin of the elements,” Rev. Mod. Phys.56, 149 (1984).G. Gamow, “Zur Quantentheorie derAtomzertrümmerung,” Zeit. fur Physik52, 510 (1928). Derives the Gamowfactor using quantum mechanics.S. Hawking, “Gravitationally collapsedobjects of very low mass,” MonthlyNotices of Royal Astronomical Society,152, 75 (1971). In this imaginative paper,Hawking speculates that the centralregion of the sun might contain a blackhole and that this could be the reasonwhy the flux of solar neutrinos wasless than predicted.H. von Helmholtz, Lecture “On theinteraction of natural forces,” Königsberg,February 7 (1854), in Phil. Mag. 11[series 4], 489-518 (1856).J. F. W. Herschel, A Treatise on Astronomy(London 1833), p. 211.W. T. Kelvin, “On the Age of the Sun’sHeat,” Macmillan’s Magazine, 288-293(March 5, 1862).J. Marchant, Alfred Russel Wallace, Lettersand Reminiscences, I (London: Cassell1916), p. 242. Letter dated 14 April,1869.W. Pauli, letter to a physicists’ gatheringat Tübingen, December 4, 1930.Reprinted in Wolfgang Pauli, CollectedScientific Papers, ed. R. Kronig and V.Weisskopf, Vol. 2, p. 1313 (Interscience,New York) (1964).H. N. Russell, “On the Sources of StellarEnergy,” Pub. Ast. Soc. Pacific, August(1919). If you like to read mystery storiesand to figure out “Who did it” fromlimited clues, then you will love thispaper. A year before Aston’smeasurements of the mass of hydrogen226JRASC December / décembre 2000

and of helium and two decades beforeBethe’s calculations of nuclear fusionrates, Russell used well-knownobservations of stars and simple physicalreasoning to infer that the rate of the“unknown process” that supplies stellarenergy must increase rapidly withincreasing stellar temperature. Incredibly,he also correctly deduced that thisdependence of energy production ontemperature would lead to stars beingstable over very long periods of time.These insights are presented in thetext of a closely reasoned lecture thatcontains no equations.E. Rutherford, “The Radiation andEmanation of Radium,” Pt. II, Technics,Aug., 171, (1904) Collected Papers, I:650.C. Smith and M. N. Wise, Energy andEmpire: A biographical study of LordKelvin, (Cambridge: CambridgeUniversity Press), 1989. This book is astimulating and authoritative accountof Kelvin, his science, and his life.Chapters 15-17 deal with the age of thesun, the cooling of the earth, and theage of the earth.C. F. von Weizsäcker, “ÜberElementumwandlungen in Innern derSterne. II,” Physikalische Zeitschrift,39, 633 (1938). The CNO cycle isdescribed in the last paragraph ofSection 7.AppendixThe p—p chain reactionIn theoretical models of the sun, the p–pchain of nuclear reactions illustrated hereis the dominant source of energyproduction. Each reaction is labeled bya number in the upper left hand cornerof the box in which it is contained. Inreaction 1, two hydrogen nuclei ( 1 H,protons) are fused to produce a heavyhydrogen nucleus ( 2 H, a deuteron). Thisis the usual way nuclear burning getsstarted in the sun. On rare occasions, theprocess is started by reaction 2. Deuteronsproduced in reactions 1 and 2 fuse withprotons to produce a light element ofhelium ( 3 He). At this point, the p—p chainbreaks into three branches, whose relativefrequencies are indicated in the figure.The net result of this chain is the fusionof four protons into a single ordinaryhelium nucleus ( 4 He) with energy beingreleased to the star in accordance withEinstein’s equation. Particles called‘neutrinos’ (v) are emitted in these fusionprocesses. Their energies are shown inthe figure in units of millions of electronvolts (MeV). Reactions 2 and 4 were notdiscussed by Hans Bethe.The figure is adapted from J. N.Bahcall, Neutrinos from the Sun, ScientificAmerican, Volume 221, Number 1, July1969, pp. 28-37.The CNO cycleFor stars heavier than the sun, theoreticalmodels show that the CNO (carbonnitrogen-oxygen)cycle of nuclear fusionis the dominant source of energy generation.The cycle results in the fusion of fourhydrogen nuclei ( 1 H, protons) into a singlehelium nucleus ( 4 He, alpha particle), whichsupplies energy to the star in accordancewith Einstein’s equation. Ordinarycarbon, 12 C, serves as a catalyst in this setof reactions and is regenerated. Onlyrelatively low energy neutrinos (v) areproduced in this cycle.The figure is adapted from J. N.Bahcall, Neutrinos from the Sun, ScientificAmerican, Volume 221, Number 1, July1969, pp. 28-37.John Bahcall has been a Professor of NaturalSciences at the Institute for Advanced Study,Princeton, NJ since 1971. He is best knownfor his research work on solar neutrinos,quasars, stars in the Galaxy, and atomicprocesses. Bahcall is a former President ofthe American Astronomical Society and ledthe survey by US astronomers to set prioritiesfor astronomical research in the 1990’s.December/ décembre 2000 JRASC227

Illustration by Brian G Segalby Patrick MooreMoon is a changelessworld.” This is certainly the“Thegeneral view, and in the mainit is correct. Very little has happened therefor a long time, and no craters have beenformed apart, no doubt, from a few smallimpact structures. Yet the Moon is nottotally inert.Most long-term observers have seentraces of activity there, in the form oflocalized glows or obscurations. They areknown as TLP or “Transient LunarPhenomena” — a term for which I admitto being responsible (I introduced itaround 1950). The reality of TLP has longbeen questioned, mainly because mostof the reports — not all — have comefrom amateur observers, but the situationnow is different. It is significant that afew professionals who paid close attentionto the Moon in the pre-Apollo period alsosaw occasional TLP; among these observerswere E.E. Barnard and W.H. Pickering.All these early reports are contained inthe TLP catalogue published by NASA in1968 (Middlehurst et al. 1968); a furtherlist appeared in 1971 (Moore 1971), andanother update is now in preparation.There are various areas which areparticularly event-prone, notably thebrilliant crater Aristarchus. Moreover,most TLP are seen near the boundariesof the regular maria, and in regions richin rills. They also seem to be commonestnear perigee, when the lunar surface isunder maximum strain.TLP became widely discussed in1959 following an observation of an eventin the walled plain Alphonsus recordedby N.A. Kozyrev from the CrimeanAstrophysical Observatory (Kozyrev 1959).In this episode I played a minor and totallyundistinguished part (Moore 1977). In1955 D. Alter, using the Mount Wilson60-inch reflector, had taken photographswhich indicated temporary obscurationsin Alphonsus. In correspondence withKozyrev, I suggested that the area wouldbe worth watching, and on November 3 rd ,1958 Kozyrev recorded a “reddish cloud”over the central peak; he obtainedspectrographic confirmation. He believedthat there had been a sharp rise intemperature. This I frankly doubt, but atleast the observation appeared to be valid,and it is worth adding that as long agoas 1882 the German astronomer Kleinhad claimed that he had seen “volcanicphenomena” inside Alphonsus.Had there been any permanentchange in the area? During the followingmonths several observers, including BrianWarner at the University of LondonObservatory, described a bright red patch.I was never able to see it, and it certainlyseems to be absent now, but anotherspectrographic observation was made byKozyrev on October 23 rd , 1959; on thatoccasion nothing unusual was seen visually.Another professional report camein 1963, when J. Greenacre and E. Barr,at the Lowell Observatory, recordedcoloured events inside the crater Gassendi(Greenacre 1965). On April 30 th , 1966,using my 15-inch reflector at Selsey inSussex, I observed an orange streak insideGassendi (Moore 1967), and this wasindependently confirmed by other observersat different sites. Over the following yearsmany reports came in — one, of specialinterest, on 23 May 1985 from the Greekobserver G. Kolovos and his colleagues,who photographed a brief TLP in thePalus Somnii (Kolovos 2000). It coveredan area of 3 × 3.5 miles and was attributedto gases sent out from below the lunarcrust. Attempts were made to explainaway this event as reflected sunlight froman artificial satellite, which just happenedto be in the line of sight, but the imagesindicated that the obscuration was linkedwith the topography of the area, so thatthe satellite theory is not at all convincing.The reality of TLP has now beenconfirmed by an observation made fromMeudon (Paris) by Audouin Dollfus, whoseexperience is second to none. Dollfuswrote (Dollfus 2000):“On 30 December 1992, glowshave been recorded at the lunarsurface, on the floor of the craterLangrenus. They were not presentthe day before. Their shape andbrightness were considerably modifiedthree days later. These glows appearedalso in polarized light. They areapparently due to dust grainlevitations above the lunar surface,under the effect of gas escaping fromthe soil. The Moon appears as acelestial body which is not totallydead.”Lunar activity is of course very mild,but it does occur, and further observationsof TLP will be of great interest. However,the greatest care must be taken, as it isonly too easy to be deceived by effects in228JRASC December / décembre 2000

“ Most long-term observers have seen traces of activity [on the Moon],in the form of localized glows or obscurations. They are known as TLPor “Transient Lunar Phenomena — a term for which I admit to beingresponsible (I introduced it around 1950).”our atmosphere. For a purely visualobservation, confirmation is needed fromat least two observers at different sites,and I am sure that many reports in theoriginal NASA catalogue are spurious.Above all, more spectra are needed, andit is hoped that the programme noworganized by the Lunar Section of theBritish Astronomical Association willproduce some results.ReferencesDollfus, A. 2000, personal communicationGreenacre, J.C. 1965, Ann. N.Y. Acad. Sci.,123, 812Kolovos, G. in Moore, P., The Moon, London2000, (in press)Kozyrev, N. 1959, Priorda, 3, 84Middlehurst, B., Burley, J., Moore, P. &Weither, B. 1968, “Chronological Catalogof Reported Lunar Phenomena”, NASATech. Rep. TR-R-277Moore, P. 1967, JBAA, 78, 138Moore, P. 1971, JBAA, 81, pp. 365–390Moore, P. 1977, “The Observation ofTransient Lunar Phenomena”, Phil.Trans. R. Soc. Lond., A285, pp. 481–483Patrick Moore has been an honourary memberof the RASC since July 1993. He is well knownfor his numerous books and articles whichhave served to popularize astronomy forgenerations.ALamplighter Moment: 1Daytime Observations ofVenus at Inferior Conjunction 2by Fr. Lucian J. Kemble, OFM (with comments by David M. F. Chapman)Abstract. The inferior conjunction ofVenus on April 3, 1985 exhibited one ofthe widest apparent separations of Venusabove the Sun (over 8°). An explanationof the phenomenon and the distinctionmade between equatorial and eclipticconjunctions is followed by descriptionsof daytime observing techniques (anddangers!). Five observations obtained atabout noon on the days immediatelybefore and after conjunction are described.Atmospheric glow was noted around thewhole disk of the planet. The author haspreviously made observations of a similarinferior conjunction of Venus on April 6,1977 (almost exactly eight years earlier)when Venus and the Sun were even closer:7°.13. A comparison is made of the twoevents and reference given to other near-Sun observations of Mercury, Mars, Jupiter,and Saturn.In Quebec City one fine sunny day of1948, when I was a young Franciscanstudent of philosophy, my confrèresand I were playing volleyball. As I leapedup to return a shot, my eyes reachedbeyond the ball and chanced to focus onVenus — my first-ever daytime view of aheavenly body other than the Sun or Moon.[There was an inferior conjunction ofVenus on June 14, 1948.] I missed the ball,lost the point and the game, and had myconfrères searching for the object of myexcited finger pointing. Thus was born anew and fascinating facet of a life-longinterest in and passion for astronomy. 3In 1972, with my first pair ofbinoculars and a Celestron-5 telescope,1Dedicated to the memory of Father Lucian Kemble (1922–1999), a.k.a. “Lamplighter,” who touched the lives of countless members of the RASC through hislove for all aspects of observing. A “Lamplighter moment” is simply an occasion where, through careful observation of the mundane, one unexpectedly discoverssomething profound, something achieved by Lucian Kemble fairly regularly during his lifetime. This section is a regular part of the Journal devoted to guestarticles by authors describing their Lamplighter moments.2Text of a paper presented at the General Assembly of the RASC, Edmonton, June 28 – July 1, 1985.3Lucian Kemble, “Daytime and Twilight Observations,” RASC National Newsletter, October 1976.December/ décembre 2000 JRASC229

“As I leaped up to return a shot [in volleyball],my eyes reached beyond the ball and chancedto focus on Venus — my first-ever daytime viewof a heavenly body other than the Sun or Moon.”I began a continuing series of excitingdaytime observations. I shall never forgetmy first noontime view of a star in thetelescope: Arcturus — a golden glitter offire-ice in a sea of blue. My searches havereached to stars as faint as the fifthmagnitude, such as the “double-double”in Lyra; to Mercury, Venus, Mars, Saturn,and Jupiter within 10° of the Sun; to Uranusand Neptune shortly after sunset; to thesplitting of otherwise difficult doubles,etc.Venus of course has retained itsspecial appeal, and very early I began towonder, when I realized that it couldsometimes pass above or below the Sunat inferior conjunction, if it would bepossible to observe it at such times.Wonder, coupled with much experienceand perfecting of technique, led to research,calculating, and plotting. The first attempt,in April 1977, was successful and wasfollowed by the more recent event in April1985.Before I describe those events, Iwould like to give a brief review of theorbital elements of Venus and Earthresponsible for these opportunities. 4 Theorbit of Venus, with a sidereal period ofrevolution of 224.7 days, is inclined tothe ecliptic by 3°.39, with ascending nodein December, maximum heliocentriclatitude north in March, descending nodein June, and maximum heliocentric latitudesouth in September. Venus returns toinferior conjunction, i.e. its synodic period,every 584 days, or roughly every 19.4months. By a curious 8/5 resonance, thatmeans that every eight Earth years Venuswill have passed through inferiorconjunction five times (almost exactly,with a difference of only 2.5 days). Seriesof similar inferior conjunctions occur inpairs of 8 years apart. Hence, when theconjunctions occur at the nodes, thereare transits of Venus across the Sun’s diskeight years apart and in pairs separatedby 122 and 115 years. The last pair oftransits was in December 1874 and 1882;the next in June 2004 and 2012. Springtimepairs, such as the two I have observed,occur near the time when Venus is atgreatest heliocentric latitude north andnearest Earth. They are therefore mostfavorably placed for observation, 5 withVenus well above the Sun, on average7°.75. The maximum separation, at 8°.3,is reached in March 2017.It may come as a surprise that thereare in reality two sorts of inferiorconjunction, depending on whether oneis speaking of equatorial or eclipticcoordinates, since the ecliptic is mostoften inclined with respect to celestialright ascension, most pronounced at theequinoxes. Thus on April 1, 1985 Venushad the same R.A. as the Sun at 12:50 MST,but it reached ecliptic inferior conjunction,with the same celestial longitude as theSun and therefore at its closest to the Sun,on April 3 at 3:00 p.m. MST. The two typesof inferior conjunction would coincideonly at the time of summer or wintersolstice, when a given planet would benorth or south of the Sun in both R.A.and celestial longitude at the same time.Daytime telescopic observationdemands some rather refined but simpletechniques and, when carried out nearthe Sun, considerable care and caution.An accurately aligned finder scope anda solid, clock-driven mount are essential,as are familiarity and practice with accuratepolar alignment. The latter can be achievedusing a permanent pier or by setting upthe night previous and leaving one’s tripodand mount outside, or at least by usingmarkers to assure setting the tripod inthe same position. With proper polaralignment assured, the main telescopeis left covered and is pointed to the Sununtil the Sun’s projected disk shines directlycentred through and on the shadow ofthe finder. With accurate solar co-ordinatesfor the specific time of observationpreviously calculated from an Ephemeris 6or The Observer’s Handbook, set the R.A.setting circle accordingly. If the Moon orVenus is in the sky, remove the telescopecover (duly pointed away from the Sun)and use the Moon or Venus to focus thetelescope more accurately. Then, usingco-ordinates, locate a bright star such asCapella, Arcturus, Vega, Betelgeuse, etc.,more accurately reset the R.A. settingcircle, and refine the focus. When a staris found, it may even be sighted in thefinder. Observing a star, Mercury, or Venusnear the Sun requires an added refinement,both to enhance observing and to reducerisk of eye damage. I use a long, tubulardew shield on the open end of the telescopetube and tape a piece of cardboard overhalf the front end of the shield, on theside nearest the Sun. This, of course, stopsdown the aperture, but it greatly cutsdown on solar glare and increases contrast.Great care must be taken to not allow thetelescope to drift freely, so that it doesnot point directly at the Sun.Frequent successful use of the aboveprocedure encouraged me to attemptobservation before, during, and following4Data obtained from the highly recommended, useful, and comprehensive Astronomical Tables of the Sun, Moon, and Planets by Jean Meeus (Willmann-Bell,Inc. 1983).5See Sky & Telescope, March 1985, p. 244, for the geometry involved.6For example, the Astronomical Almanac published annually by the U.S. Government Printing Office, Washington, DC; obtainable from Willmann-Bell, Inc.230JRASC December / décembre 2000

the inferior conjunction of Venus on April6, 1977, when the planet was 7°.13 abovethe Sun. At the time I was using a piermountedCelestron-8 telescope. WithVenus moving rapidly westward, I foundit most rewarding to see the extremelythin, sunlit crescent of the planet’s hugedisk slide around from lower right of theSun before conjunction, to directly under,then to lower left afterwards.The similar event eight years laterhappens 2.5 days earlier each cycle, so in1985 it occurred at 22 hours UT on April3. Both events, in 1977 and 1985, fortunatelyhappened on our daylit side of the globe.In preparation for the event, I calculatedvery exactly the co-ordinates for boththe Sun and Venus for every day at 20:00hours UT (1:00 p.m. MST) from March27 to April 8 inclusive, using data in theAstronomical Almanac. Using the piermountedCelestron-11 telescope, I achievedsuccessful observations on March 29,March 31, and April 1 with Venus exactlynorth of the Sun, and on April 5 and April6, i.e., three good observations beforeinferior conjunction and two following.The day of closest approach, unfortunately,was cloudy. On all occasions the 59arcsecond-diameter disk of Venus wasfully seen and best observed at 166× inan eyepiece with an orange filter. Extendingfrom the elongated cusps of the very thincrescent, lit from behind and below, therewas an atmospheric glow completelyencircling the disk. The so-called ashenlight was not observed. My best view washad at mid-morning, April 5, with Venus8°.05 from the Sun. I noted a slightbrightening of the atmospheric glow onthe upper rim exactly opposite the centreof the sunlit crescent. A visitor at my site“Without being coached or told what to look for,she exclaimed, “I can see the whole roundplanet, with a soft glow all the way around.”In all, a pleasant rebuttal to some of my friendswho sometimes jokingly remark when I spota faint object, “Lucian, you’re seeing things!””provided an interesting confirmation ofthe observation on that occasion. Shehad never looked through a telescopebefore and was greatly thrilled at seeingthe gorgeous crescent. Without beingcoached or told what to look for, sheexclaimed, “I can see the whole roundplanet, with a soft glow all the way around.”In all, a pleasant rebuttal to some of myfriends who sometimes jokingly remarkwhen I spot a faint object, “Lucian, you’reseeing things!” Wind and heat turbulenceprevented any photographic record ofthe event. 7I have succeeded on other occasionsin obtaining daytime photographs ofArcturus, Jupiter, and Venus in its crescentphases. And, of course, I have enjoyedmany fine visual daytime observationsbesides those mentioned: Mercury asclose as 10° to the Sun, Saturn 12° westof the Sun, Saturn at 2:00 p.m. on the dayof the Voyager 2 fly-by, the April 7, 1976occultation of Geminorum by Mars(mine was one of only three daytimeobservations reported to Sky & Telescope 8 ),the seven brightest stars of the Pleiades,etc. An interesting note about Venus:since it is possible to view the planet closeto the Sun and sometimes even throughinferior conjunction, one can see Venusalmost any day of the year, to within itsgreatest elongation of 47°. The only timeit is hidden by solar glare is a week or soeither side of superior conjunction.I encourage other RASC membersto try their hand at this aspect of theirobserving programmes, taking advantageof the long summer twilight hours in ournortherly latitudes. Be prepared for somemore forthcoming inferior conjunctionsof Venus: August 22, 1991, 8°.23 south ofthe Sun; April 1, 1993, 7°.87 north of theSun (i.e. the next eight-year cycle); and,of course, for those of us/you still around,the great pair of transits in June 2004 and2012. Good Luck![The next inferior conjunction ofVenus of the type described above takesplace on March 30, 2001, continuing theeight-year cycle 1977, 1985, 1993… A fewdays earlier, on March 27 and 28, Venusis more than 5° above the horizon atboth sunrise and sunset, providing anopportunity to view Venus as an eveningstar and a morning star on the sameday.]7See Sky & Telescope, April 1985, p. 340, for a photograph of a similar event.8Sky & Telescope, June 1976.December/ décembre 2000 JRASC231

ReflectionsNew Year ‘s Dayby David M.F. Chapman (dave.chapman@ns.sympatico.ca)Have you ever wondered why NewYear’s Day is January 1 st ? Thatmay seem to be a silly question,but it has not always been so: historicallyspeaking, New Year’s Day has wanderedaround the calendar, and there alwayshave been calendars that start on daysother than January 1 st . (I once asked aChinese woman how to determine thedate of Chinese New Year. Giving me astrange look, she replied “You look onthe calendar!”)The calendar we use today, and whichthe world commonly uses for civil purposes,has its origins in the 365-day Egyptiansolar calendar. The flooding of the Nilewas a key date in Egyptian agriculture,a yearly event driven by the annual motionof the tilted Earth around the Sun. Thepeak of the flood happened to coincidewith the heliacal rising* of Sirius, the DogStar (Alpha Canis Majoris), and New Year’sDay on the Egyptian calendar occurredduring the “dog days” of what we now callAugust.Another source of our moderncalendar — at least for month names —is the Republican Roman calendar, whichwas a type of lunar-solar calendar. Thiscalendar started when the Earth itselfwas observed to experience rebirth, onthe first day of the month of Martius(March). Evidence of the March beginningcan be found in today’s month names.Following Martius, there were Aprilis,Maius, and Junius. The early Romans ranout of name ideas after 4 months, andthey simply numbered the next months:Quintilis, Sextilis, September, October,November, December. Bringing up therear were Januarius and Februarius, lateradditions. You can begin to understandwhy the leap days in calendars to comewere inserted into the month of February:it used to be the last month of the year.The republican Roman calendar provedto be unsatisfactory, often being arbitrarilymodified by minor officials whose questfor personal gain outweighed the publicgood.In 46 bc Julius Caesar (with expertadvice from the Alexandrian astronomerSosigenes) reformed the Roman calendarafter the Egyptian model. During the“Year of Confusion,” he inserted 67 daysto put it in step with the seasons,introduced the well-known 4-year cycleof leap years, and confirmed New Year’sDay as January 1 st , bringing it closer tothe Winter Solstice. Following Caesar’sassassination, the month Quintilis wasrenamed Julius, and eventually the monthSextilis was renamed Augustus after Julius’grand-nephew, who was the first RomanEmperor. Starting the year in January putthe last four months of the year innumerical positions two beyond thosesuggested by their names. (I struggle withthis constantly: September is 9, Octoberis 10, November is 11, December is 12.)These month names and their order havepersisted to this day, even during theascent of the Church as a unifying politicalpower.Meanwhile, many pagan culturessimply divided the year into quarters, thequarter days being the Equinoxes andthe Solstices. Traditionally, these wereMarch 25 th , June 24 th , September 26 th , andDecember 25 th on the Julian calendar, butthe true dates of the astronomicalphenomena immediately began slippingearlier, due to a small imprecision in thelength of the Julian year. Dividing further,the cross-quarter days were midwaybetween the quarter days: occurring inearly May, August, November, and February,these days are cluster points for traditionalfestivals which have survived to the presentday. This is described well in Guy Ottewell’sAstronomical Companion. The Celtic yearbegan with the gloomy festival of Samhain,which survives today as Hallowe’en followedby All Saints Day. The Germanic tribes,and others, began their year with theWinter Solstice.The Christians helped spread theuse of the Julian calendar, but they weremostly interested in keeping the date ofEaster near the Vernal Equinox, whichhad become the focus of the ecclesiasticalyear. Early Church leaders were wary ofthe pagan rituals that took place aroundthe Winter Solstice and decided thatMarch 25 th (the traditional date of theVernal Equinox) made a better New Year’sDay. Better yet, in the Church calendar,March 25 th is Annunciation Day, exactly9 months before the December 25 th , whichhad been chosen as Christmas Day, thecelebration of the birth of Christ.** Inmany European countries, includingEngland, March 25 th was New Year’s Daywell into the Second Millennium.In 1582 Pope Gregory XIII reformedthe Julian calendar, correcting the backwardslide of the Equinoxes and the Solstices.He also standardized New Year’s Day asJanuary 1, one week after the traditionaldate of Christmas. It took time forProtestant countries to toe the line; forexample, England and its colonies didnot make the calendar shift until 1752.The ghost of March 25 th lingers on: whenEngland made the change, March 25 thJulian was the same as April 5 th Gregorian,*The heliacal rising of a star is the first appearance in the morning sky of a star which was previously invisible owing to its conjunction with the Sun.** There is little evidence that Jesus was born in December. A better case could be made for the spring, when shepherds would indeed “watch their flocks bynight,” as this is the lambing season.232JRASC December / décembre 2000

and April 5 th still marks the start of theUK Taxation Year.What I have just written is a muchsimplifiedversion of the story. A recentbook that delves into minute detail onthe history of our calendar is DuncanSteel’s Marking Time (John Wiley & Sons,New York, 2000). A similar book (with aslightly pompous title) is David Duncan’sCalendar: Humanity’s Epic Struggle toDetermine a True and Accurate Year (AvonBooks, New York, 1998). A lighter read isIsaac Asimov’s The Clock We Live On(Collier, New York, 1963), but this hasbecome hard to find. (My copy is a batteredpaperback.)* * *Expect widespread confusion over datesin the coming year. Despite all the hooplalast year about Y2K and the demise ofcivilization, very little attention has beenpaid to the fact that the world has notsettled on an unambiguous date standardfor printed records and forms. Up untilnow we have suffered with DD/MM/YYand the U.S. variant MM/DD/YY. I havealso seen YY/MM/DD. The year 2000 wasa grace period, since “00” could onlyrepresent the year. Now we will be presentedwith dates like 03/02/01, and we will beleft scratching our heads. In these pagestwo years ago, I made a plea to adopt theISO date standard: YYYY-MM-DD. I willnot repeat my argument; I think thestandard speaks for itself. Since that time,several people have criticized the standardon the basis of its awkwardness in speechand writing: it is simply not the way weexpress ourselves colloquially. To this Iwould have to agree. ISO never meant tostandardize speech and writing, only inthe representation of dates used inelectronic data processing andcommunication. By all means say “Thesecond of January, 2001” or write “2001January 1” if you want. My amended appealis “please use the ISO standard in caseswhere only numbers are used to representthe date.” Be careful out there.David Chapman is a Life Member of theRASC and a past President of the HalifaxCentre. Visit his astronomy page atwww3.ns.sympatico.ca/dave.chapman/astronomy_page.As they say…be careful whatyou wish for…!December/ décembre 2000 JRASC233

FROM THE PASTFROM THE PASTAU FIL DES ANSAU FIL DES ANSTHE LENGTH OF THE YEARThe following note arose from inquiries over the telephone which revealed that considerable confusion prevails in the use of the termyear. Perhaps the writer may be pardoned for an attempt to elucidate the matter here.The two chief units of time are the day and the year. The former is the rotation-period of the Earth on its axis; the latter, itsrevolution-period round the Sun.At the instant when the centre of the Sun is on the meridian we say it is solar noon, and the interval between two successivesuch noons is a solar day. The lengths of such intervals are not all equal, and their average length is a mean solar day. This is the dayin common use; it contains 86,400 seconds as ticked off by your watch.How shall we determine the length of the year? While we are persuaded that the Earth revolves about the Sun, to us the Sunappears to move, in the course of the year, about the sky in a circle which we call the ecliptic, and which intersects the celestialequator in two points. When the Sun is at one of these points as it is moving from the south side to the north side of the celestialequator, it is the spring equinox (March 21); when at the other, it is the autumn equinox (September 23). The interval from one springequinox to the next one is a tropical year, or a year of the seasons. By it our lives are governed. Such years vary in length considerably,and their average length is 365d. 5h. 48m. 46s. (approximately).It may be interesting to give the actual length of some of these tropical years. In the Observer’s Handbook is stated each yearthe date of the spring equinox, correct to one minute, and by writing down these dates for a series of years one can calculate thelength of the tropical year elapsing from one equinox to the next. In this way the following table was prepared for years 1928-45.Year Equinox Length of Yeard h m d h m1928 Mar. 20 15 45 … . ..1929 Mar. 20 21 35 365 5 501930 Mar. 21 03 30 365 5 551931 Mar. 21 09 07 365 5 411932 Mar. 20 14 54 365 5 471933 Mar. 20 20 43 365 5 491934 Mar. 21 02 28 365 5 451935 Mar. 21 08 18 365 5 501936 Mar. 20 13 58 365 5 401937 Mar. 20 19 45 365 5 471938 Mar. 21 01 43 365 5 581939 Mar. 21 07 29 365 5 461940 Mar. 20 13 24 365 5 551941 Mar. 20 19 21 365 5 571942 Mar. 21 01 11 365 5 501943 Mar. 21 07 03 365 5 521944 Mar. 20 12 49 365 5 461945 Mar. 20 18 38 365 5 49It will be seen that the year 1931 was 17m. shorter than the year 1938.The cause of this variation lies partly in the attraction of the other planets, particularly the massive Jupiter and Saturn, upon theearth, helping it forward at some parts of its orbit and holding it back at others.The remainder of the variation is due to changes in the position of the equinoxes themselves; this is known as nutation, and isproduced by varying lunar attractions.by C. A. Chant,from Journal, Vol. 39, pp. 30–31, January, 1945.234 JRASCDecember/ décembre 2000

Second Light“Of Pale Kings and Pyramids”by Leslie J. Sage (l.sage@naturedc.com)When I was a child, I likedEgyptian mummies almost asmuch as I liked stars, and theEgyptian galleries at the Royal OntarioMuseum were a favourite place. Thirtyyears later, it gives me great pleasure towrite about stars and mummies. Althoughthe subject of this column is somewhatdifferent than usual, I hope that my readerswill enjoy the topic as much as I do.It is a commonly held, but erroneous,view that people living in ancient timeswere not as intellectually sophisticatedas we are today. In fact, given thetechnological and engineering limitationsof the times, they often came up withextremely elegant solutions to practicalproblems. Aficionados of astronomy knowthat the ancient Greeks proved that theEarth is a sphere orbited by the Moon,and that the Moon shines by reflectedsunlight. Less well known is that someof the pyramids of ancient Egypt arealigned with rather uncanny precisionto true north. Writing in the journalNature, Egyptologist Kate Spence, of theUniversity of Cambridge, has recentlyshown, however, just how simply thisalignment was possibly achieved 4500years ago, during the Old Kingdom.The precision in the pyramidalignments is uncanny because at thattime there was no north star to act as aheavenly marker. The nearest relativelybright star to the celestial pole around2600 bc was about 2 degrees from truenorth, while the alignment of the GreatPyramid at Giza is only 3 arcminutes fromnorth. Even today, using Polaris, pyramidbuilders would not be able to achieve theprecise alignment realized around 2550bc, because Polaris is almost a degreeaway from the north celestial pole.“The precision in the pyramid alignments isuncanny because at that time there was nonorth star to act as a heavenly marker. Thenearest relatively bright star to the celestialpole around 2600 BC was about 2 degrees fromtrue north, while the alignment of the GreatPyramid at Giza is only 3 arcminutes from north.”You might imagine that the Egyptianscould have used the transit of the noonhour Sun, then turned to face the oppositedirection, to find north. But the Sun isabout half a degree across, and the sourceof considerable heat — which disturbsthe seeing — so the errors in alignmentwould most probably be randomly scatteredover at least a degree. Using the transitof the Moon or a single star might producebetter results, although the size of thefull Moon is also about half a degree onthe sky.But the curious thing about thealignments of the pyramids is that theprecision does not vary randomly with aGaussian (or bell curve) distribution, asone would expect if the measurementshad been made using transits of the Moonor single stars. In fact, the alignmentsduring the Old Kingdom start off relativelybadly (about 20 arcminutes from north),get better over the space of about 50 years,then get worse again for another hundredyears. You would think that if the Egyptianshad worked out an absolute system ofdetermining north, they could continueto apply it with equal precision over thespace of several hundred years, given thattheir civilization lasted several thousandyears.Spence has found a technique withvariable accuracy that fits very well withthe observed precision of the alignments.She proposes that the Egyptians used thesimultaneous transit of two relativelybright circumpolar stars to determinenorth; one star would be at its uppermostpoint, heading west, the other would beat its lowermost point, heading east. Atthe time of the transits, surveyors coulddrop a plumb line against the lineconnecting the two stars to lay out thewestern edge of the pyramid. This isintrinsically much more accurate thanusing the transit of a single circumpolarstar. And, because of the precession ofthe Earth’s orbit, the technique is variablein time.By definition, if the transits aresimultaneous, the line connecting thetwo stars in the sky passes through thenorth celestial pole. But that will be trueonly for a relatively brief period of time(a year or so, in fact). At other times, onestar will transit slightly ahead of the other,and a vertical line connecting them —December / décembre 2000 JRASC235

The west side of the Great Pyramid of Giza was aligned to the northcelestial pole 4500 years ago, with an astonishingly small error ofabout 3 arcminutes. Spence’s recalibrated chronolgy of the Old Kingdomindicates that Khufu’s reign began in 2480 +/– 5 BC, rather than the2254 BC previously believed. Photograph courtesy of Kate Spence.against which the surveyors dropped theirplumb line — will not pass directly throughnorth. As the Earth’s orbit precesses, thedifference in time between the upper andlower transits increases, and thereforethe alignment error also increases.In order to determine which pairsof stars were viable candidates, Spenceused a standard precession program. Onlytwo pairs of stars could have been usedaround that time: ζ Ursae Majoris —β Ursae Minoris, or εUrsae Majoris — γUrsae Minoris. The firstpair had simultaneoustransits around 2467bc, while the secondpair had them around2443 bc. To gaugewhich pair of stars theEgyptians might haveused, Spence plottedthe errors in alignmentthat would result fromeach pair; the ζ UrsaeMajoris — β UrsaeMinoris combinationhad exactly thecharacteristics of themeasured alignmenterrors. She shows thatalignments of six out ofeight pyramids builtduring that time fall rightalong a straight line oferror versus time, if thesurveying was donebetween the summerand autumnal months.The two anomalouspoints, though, are whatreally clinch the case. Ifthe surveying for theother two pyramids wasdone sometime duringthe winter or springmonths, the error inalignment would havethe opposite sign, because circumpolarconstellations have opposite positionsin the sky, relative to the north celestialpole, when separated by six months intime. Simply reversing the sign of theerror of those two anomalous pyramidsbrings them right into agreement withthe others.Leading up to the year or so whenthe stars transit simultaneously, themethod will produce ever more accuratealignments, and afterward the techniquebecomes increasing less precise. At somepoint, the difference in transit times wouldhave become so noticeable that thetechnique was abandoned, and for thenext 500 years the errors in alignmentsseem to scatter randomly (though thereare few data points in the latter timeperiod).The result of modeling the errorsarising from the astronomical facts, andthen fitting the observed errors inalignments of the pyramids, is that thesurveying for the Great Pyramid seemsto have been done about 2478 +/– 5 bc.This result provides a precise anchor pointfor Old Kingdom chronologies, becauseit is generally accepted that the surveyingwas done early in the king’s reign.The only problem is that this anchorpoint is about 74 years later than thecommonly accepted chronology. Spencepoints out that it is not possible simplyto slide the whole accepted chronologyforward by 74 years because there aredates soon after 2000 bc that also havebeen fixed by astronomical observations.This means that the Old Kingdomchronology will need to be compressed,which will require a careful reassessmentof the historical data. Spence is about tostart surveying pyramids for which thereare no accurate alignment data and hopesthat with additional modeling she canproduce for two kings accession datesthat are accurate to plus or minus one ortwo years — quite an achievement, forevents that happened so long ago.Dr. Leslie J. Sage is Senior Editor, PhysicalSciences, for Nature Magazine and a ResearchAssociate in the Astronomy Department atthe University of Maryland. He grew up inBurlington, Ontario, where even the brightlights of Toronto did not dim his enthusiasmfor astronomy. Currently he studies moleculargas and star formation in galaxies, particularlyinteracting ones.236JRASC December / décembre 2000

Research PapersArticles de rechercheSPACE MIRROR EXPERIMENTS: A POTENTIALTHREAT TO HUMAN EYESby James G. LaframboisePhysics and Astronomy Department, York University, TorontoElectronic Mail: laframboise@quasar.phys.yorku.caand B. Ralph ChouSchool of Optometry, University of WaterlooElectronic Mail: bchou@sciborg.uwaterloo.ca(Received June 27, 2000; revised September 29, 2000)Abstract. We show that space-mirror experiments reflecting sunlight to Earth can produce resolved images having surface-brightnesssufficient to damage human eyes looking through telescopes or binoculars.Résumé. Nous démontrons que les essaies avec le mirroir spacial qui réflète les rayons du soleil sur la Terre peuvent, à l’aide de télescopesou de jumelles, produire des images dont la face est suffisammant brillante pour endommager l’oeil humain.SEM1. IntroductionAstronomers have expressed alarm over possible long-range implicationsof the Russian Znamya space-mirror experiment, which was attemptedwith partial success in 1993 (Sky & Telescope 1999) but unsuccessfullyin 1999 (Sky & Telescope 1999; Toronto Globe and Mail 1999). Thisexperiment may be attempted again. A more immediate concernwith this experiment appears to have been overlooked, namely thepossibility of eye damage to anyone on the ground who uses binocularsor a telescope to look at the spot of light in the sky. The danger wouldbe similar to that involved in looking at the Sun just before or after atotal eclipse. In both cases, the risk is that the eye is exposed to theSun’s full surface-brightness over a very small solid angle, too smallto prevent the eye from being fully dark-adapted and therefore mostsensitive to damage, but large enough that an image of some portionof the Sun’s surface is fully resolved on the eye’s retina. We presentresults of two separate calculations, both of which indicate that thisdanger is real.In order to examine this issue, we have used information fromnews reports of the second attempt of the Znamya experiment (Sky& Telescope 1999; Toronto Globe and Mail 1999). According to thisinformation, the illuminated region on the ground was to have adiameter of 6 to 8 km. The spacecraft’s orbital altitude was 225 milesor about 360 km. Dividing 360 by 6 gives a beam-spread of 1/60 radian,or about one degree. Since the Sun itself subtends an angle of abouthalf a degree, this rather small anticipated beam-spread implies thatthe mirror, which was made of aluminized flexible plastic sheeting,would have been nearly flat, with irregularities of about half a degreeor less. Therefore, near the centre of the beam, an observer wouldhave seen a surface-brightness close to that of the Sun.2. Rudimentary CalculationWe consider first an amateur astronomer looking through an 8-inch(20 cm) telescope, which has an angular resolution of about one arcsecondin the best atmospheric seeing conditions. At a distance of360 km, the length which subtends this angle is: 360,000 m / 3,600arc-seconds per degree ×π/180 radians per degree = 1.75 metres.Therefore, an object must be at least this large to be fully resolvedat this distance. Since the Znamya mirror in the 1999 attempt wasto have had a diameter of 25 m, it would have been fully resolved.Therefore, if an amateur astronomer happened to be observing withsuch a telescope at lowest power, so that the telescope’s exit pupil andhis/her eye’s dark-adapted entrance pupil were well-matched at about7 mm each, and Znamya’s illumination came into view, a serious riskof eye damage would have existed.If someone merely looked at Znamya’s illumination throughstandard two-inch (7 × 50) binoculars, the minimum resolvable objectsize would then be four times larger, or about 7 m. Again, this issubstantially less than the diameter of Znamya’s mirror, so risk of eyedamage would be implied in this case also.Would the period of illumination have been too brief to causeeye damage? The spacecraft orbited at a speed of 8 km s -1 , so if theorientation of its mirror were unchanging, the illuminated spot wouldthen take roughly one second to pass over an observer on the ground.This would not have been long enough to cause significant eye damage(Ham et al. 1980). However, the Toronto Globe and Mail 1999 alsogives the locations of nine cities, at each of which the light was plannedto shine for about three minutes, presumably as a result of deliberateaiming of the light-beam at those cities. There, the hazard would havebeen greater, and the likelihood of substantial numbers of peoplelooking at the illuminated spot with binoculars would have been veryDecember / décembre 2000 Journal of the Royal Astronomical Society of Canada, 94: 237—240, 2000 December 237

great. However, the mirror failed to deploy during attempts on twosuccessive days by the crew of the Mir space-station. The Progresssupply-spacecraft on which the mirror was mounted was then separatedfrom Mir and reentered the Earth’s atmosphere.What about the risk to a naked-eye observer? The angularresolution of the eye is usually between 45 and 60 arc-seconds, so theminimum resolvable object size would then be roughly 80 to 100 m.This is larger than Znamya’s mirror, but only by a factor betweenroughly three and four. To protect itself during the daytime, the eyedecreases its aperture by approximately a factor of two, but the lowlevels of total illumination from Znamya would be insufficient tocause such a decrease. Therefore, a naked-eye observer would be safeby only a narrow margin. Larger mirrors would pose a greater risk.For an observer looking through an 8-inch telescope, “Iridiumflashes” (Chien 1998) are safe by a similar margin. The Iridium satellitesorbit at higher altitudes than Znamya’s: a temporary orbit at 500 kmwhile their performance is verified, followed by an operational orbitat 792 km (Chien 1998). Their “main mission antennas” are flat, highlyreflective rectangles whose dimensions are 1.88 m × 0.86 m (Chien1998). At 500 km, these antennas would subtend 0.78 arc-second ×0.36 arc-second = 0.28 square arc-second at normal incidence; at 796km, the corresponding values are 0.49 arc-second × 0.22 arc-second= 0.11 square arc-second. These values are below the limit of resolutionof an 8-inch telescope, but not by large factors.In bright sunlight, the eye also protects itself by an aversionreflex which limits its exposure times to roughly one second. However,this reflex becomes inactive at the low levels of total illuminationwhich occur in eclipse conditions or in the situation studied here.3. Detailed CalculationWe make the following assumptions: mirror 25 m in diameter,aluminum-coated with reflectance 0.90, at a distance of 360 km abovethe Earth’s surface; mirror segmented with 30% less reflecting areathan that of a continuous mirror (Sky & Telescope 1999); diameter ofilluminated area on surface of Earth = 6 km; uniform illuminationacross target area; air mass 1 with the mirror perpendicular to theline of sight (worst case); mirror viewed with 7 × 50 binoculars with7 mm pupil in observer’s eye (young adult).We calculate ocular exposure as follows:Solar irradiance at Znamya orbit = 1367 W m -2 with 49.6% reachingthe ground (Pitts & Kleinstein 1993a);Radiant flux collected by Znamya and reflected to Earth: P vis = 1367× 0.496 ×π×12.5 2 × 0.70 × 0.90 = 2.097 × 10 5 W;Irradiance in the illuminated zone: E vis = 2.097 × 10 5 / (π×3000 2 ) =7.42 × 10 -3 Wm -2 ;Radiant flux collected by 50 mm objective: P bin = 7.42 × 10 -3 ×π×0.025 2 = 1.456 × 10 -5 W.We allow for 98% transmittance through optics of binoculars and72.5% transmittance through ocular media, and we assume anemmetropic (normal) eye with posterior focal length 22.22 mm andrefractive index 1.333 (Pitts & Kleinstein 1993b).We calculate retinal image size as follows:Angle subtended by Znamya mirror = arctan (25/360000) = 0.004degree;Apparent size when viewed through binoculars: 0.028 degree = 100.8arc-second;Retinal image size = (22.22 tan 0.028)/1.333 = 0.00815 mm = 0.000815cm.Therefore the retinal irradiance is: E ret = 1.456 × 10 -5 × 0.98 × 0.725 /(π×0.000407 2 ) = 19.88 W cm -2 .We compare this with viewing the Sun with unaided eye with3 mm pupil through air mass 1:Retinal image size = (22.22 tan 0.5)/1.333 = 0.145 mm = 0.0145 cm.The retinal irradiance now is: E ret = 1367 × 0.496 × 0.725 × (0.0015/0.0073) 2= 20.76 W cm -2 .4. DiscussionThese calculations assume a geometry which permits the Znamyamirror to irradiate a circular spot on the surface of the Earth directlybelow it with uniform illumination at normal incidence. In reality,the departure of the beam from normal incidence at the Earth’s surfacemay be significant, and an increased air mass must then be takeninto account. In this sense, our detailed calculation represents a worstcasescenario. However, within the illuminated zone, the irradianceis not uniform from edge to edge, but is peaked towards the centre(Appendix). Our calculation is therefore conservative, because it mayunderestimate the actual ocular exposure for a ground-based observerviewing Znamya through 7 × 50 binoculars from a location near thecentre of the illuminated zone.The flatness of the Znamya mirror is a crucial issue in ourcalculations. As noted in Section 1, available data on the secondZnamya attempt imply an intended flatness to within half a degree.In comparison with this, a photo of the deployed mirror in the firstattempt (Sky & Telescope 1999) appears to show substantially morewrinkling. Even with this wrinkling, and “although much of the targetarea was blanketed by clouds, a few observers reported seeing a onesecondflash nearly as bright as the full Moon” (Sky & Telescope 1999).In that experiment, the mirror’s diameter was 20 m (Sky & Telescope1999), so this brightness was concentrated within a subtended angleof about 11 arc-seconds, which is approximately 4 to 5 times smallerthan the limit of resolution for a naked-eye observer. In this case, therelative brevity of the flash probably prevented the use of binocularsor telescopes. This factor may have fortuitously combined with thewrinkling and/or the limitation of the number of observers by cloudyconditions to prevent any cases of eye damage from having beenreported.Retinal photoreceptors at the centre of the fovea (cones on thevisual axis of the eye) have centre-to-centre spacing of approximately2 m (Bennett & Rabbetts 1989). The retinal image of Znamya, whenviewed through 7 × 50 binoculars, would therefore cover approximately16 foveal cones. The computed retinal irradiance level is 96% of the238JRASC December/ décembre 2000

level for daylight unaided exposure with the Sun at the zenith. Thusthe threshold exposure duration for photochemical retinal damagefor observing Znamya is only slightly longer than that required forthreshold damage from unaided sungazing.While the retinal image of Znamya is extremely small, it has avery high associated retinal irradiance. It could be a very seriousretinal hazard when viewed through binoculars or telescopes.On every clear day, near the beginning of sunrise and the endof sunset, most of the Sun’s disk is obscured by the Earth’s limb, andhumans would therefore face an equivalent ocular hazard, exceptthat the large intervening air mass which is present in such situationsprotects us. An astronaut on an airless moon or planet would facesuch a hazard at these times, or even if most of the Sun’s disk wereobscured by an opaque object such as a large rock, unless his spacesuitprovided visual protection greater than that from air mass 1. Equivalently,if an astronaut were to travel substantially farther than 1 AU fromthe Sun, so that the resulting decrease in solar irradiance caused hiseyes’ entrance pupils to expand significantly, he would be subject toeye damage unless he were farther than roughly 40 AU from the Sun,so that it was no longer fully resolved on his retinas.We are grateful to P.A. Delaney, M.M. DeRobertis, M.L. McCall, andthe referees, for valuable discussions and comments. This work wassupported by the Natural Sciences and Engineering Research Councilof Canada under grant A-4638, and by the Canadian OptometricEducation Trust Fund.James G. LaframboisePhysics and Astronomy DepartmentYork University4700 Keele StreetToronto, Ontario, M3J 1P3Therefore, as viewed by an observer at the centre of the illuminatedspot on the ground, every part of the mirror would be seen to bereflecting some portion of the Sun’s surface: so for this observer, themirror would be seen as fully illuminated.For an observer located at a distance r from the centre of theFig.1 — All 3 km disks inside a 6 km circle will overlap at its centre.illuminated spot, we calculate the fractional irradiance as follows.We note that the centres of the 3 km disks all lie within a radius of 1.5km from the centre of the 6 km illuminated spot (Figure 2). We assumethat within this 1.5 km radius, these centres are distributed randomly(uniformly), implying that the tilts of all the small mirrors in theB. Ralph ChouSchool of OptometryUniversity of WaterlooWaterloo, Ontario, N2L 3G1AppendixVariation of Irradiance Acrossthe Illuminated SpotAs noted in Section 1, the announced width of the spot of light onthe ground was to have been 6 to 8 km in the second Znamya attempt.We again assume 6 km, because this gives us the “worst case.” Also, 8km may correspond to nonvertical incidence of the beam. Again, 6km corresponds to an angular width of the spot on the ground of aboutone degree, as seen from the spacecraft. In comparison, the anglesubtended by the Sun’s disk, at the Earth, is about 1/2 degree, andtherefore, a perfectly flat mirror would produce a spot of light about3 km wide on the ground (1/2 degree ×π/180 radians per degree ×360 km = 3.14 km). Also, tilting such a mirror by half a degree woulddisplace such a spot about 3 km. Since 3 km + 3 km = 6 km = theassumed width of the spot on the ground, the Znamya mirror, asannounced, can be considered as a mosaic of smaller flat mirrorswhose maximum tilt relative to each other is 1/2 degree. We note thatall 3 km disks inside a 6 km circle will overlap at its centre (Figure 1).Fig. 2 — An observer at radius r sees an amount of illumination proportionalto the area of overlap between the two 3 km disks shown. The disk whoseboundary is shown as dashed contains the central points of all the overlappingilluminated spots. The other 3 km disk contains all such points located within1.5 km of the observer.December/ décembre 2000 JRASC239

assumed mosaic are distributed in the same way. Therefore, an observerat radius r from the centre of the 6 km spot will see illumination fromall 3 km disks whose centres lie less than 1.5 km from his/her location,and this observer will then see an irradiance proportional to the areaof overlap of the two 3 km (diameter) circles shown in Figure 2.We calculate this area as follows. We choose a new origin halfwaybetween the centres of the two 3 km circles in Figure 2. Then theundisplaced circle has the equation:22 2⎛ r ⎞ 2 ar a⎜ x + ⎟ + y = ⎛ xy⎝ ⎠ ⎝ ⎜ ⎞⎟ ⇒ =− ± ⎛ ⎠⎝ ⎜ ⎞±⎟ −2 2 2 2⎠For a separation distance r between these two centres, the overlaparea A(r) is now given by:y a 2 2= r1 2 2( ) −( ) a − r ⎡ 2a r⎤A= 4 2 2x+dy = ⎢ − y − ⎥∫422 dyy=0 ∫0⎢ 4 2⎥⎣⎦= −1 1 2 2 cos ( r/a) a − r2 22a − ⎛ r⎞r=∫a cos d− 2r = ⎜ ⎟ −=∫dy cos 002 ⎝ a⎠2221 2 2a −rthat subtended by the Sun’s disk. We have also ignored effects of solarlimb-darkening on this result.ReferencesBennett, A.G., & Rabbetts, R.B. 1989, Clinical Visual Optics, 2nd Ed. (Butterworth-Heinemann: Toronto), 25Chien, P., “Have you been flashed by iridium?” Sky & Telescope, May 1998,pp. 36–41Ham, W. T., Jr., Mueller, H. A., Ruffolo, J. J., Jr, & Guerry, D., III. 1980, Solarretinopathy as a function of wavelength: its significance for protectiveeyewear. In “The Effects of Constant Light on Visual Processes,” eds.T.P. Williams & B.N. Baker (Plenum: New York), pp. 319–346Pitts, D.G., & Kleinstein, R.N. 1993a, Environmental Vision: Interactions ofthe Eye, Vision, and the Environment (Butterworth-Heinemann:Toronto), 103Pitts, D.G., & Kleinstein, R.N. 1993b, Environmental Vision: Interactions ofthe Eye, Vision, and the Environment (Butterworth-Heinemann:Toronto), pp. 157–159“Znamya Flies Again,” Sky & Telescope, February 1999, 19“Sunlight at Night,” Toronto Globe and Mail, 4 February 1999, A14As r 0, A 1⁄4 a 2 , as expected. As r a, A 0, also asexpected. Therefore the normalized irradiance I(r)/I(0) is equal to:⎡ 2a ⎛ r⎞r ⎤ ⎛ 2a ⎞−1 2 2 Ar ()/ A()=0 ⎢ cos ⎜ ⎟ − a −r⎥ /⎣⎢2 ⎝ a ⎠ 2⎜ ⎟⎦⎥⎝ 4 ⎠⎡⎛ r ⎞ r r= ⎢⎜ ⎟ − − ⎛ 2 ⎤2−1⎝ a ⎠ a ⎝ ⎜ ⎞cos1 ⎟⎥ ⎢a ⎠ ⎥⎣⎦This result is plotted in Figure 3. The sharpness of the peak in Figure3 is a consequence of our fortuitous assumption that the anglesubtended at the spacecraft by the illuminated spot is exactly twiceFig. 3 — Variation of normalized irradiance (energy per unit area) withdistance across the illuminated spot on the ground.JAMES G. LAFRAMBOISE is an amateur astronomer and aprofessional physicist. His professional interests involve analyzingthe electrically disturbed regions which are created around spacecraftby their plasma environment. He has worked closely with spacecraftexperimenters in studies of high-voltage antennas, instrumentsfor electrical measurements, electrical discharge hazards, currentcarryingtethers, and high-voltage electric power systems. As anamateur astronomer, he has benefited enormously from hisassociation with the professional astronomers at the York UniversityAstronomical Observatory. He especially enjoys Messier-hunting,star parties with astronomy students, and giving tours of theuniverse to young people of all ages. He is keenly interested in thebattle against light-pollution.B. RALPH CHOU is an Associate Professor of Optometry at theSchool of Optometry, University of Waterloo. His research is inenvironmental and industrial eye hazards, particularly ocularprotection from optical radiation and impact hazards. He isAcademic Editor of the Canadian Journal of Optometry and ViceChair of the Canadian Standards Association Technical Committeeon Industrial Eye and Face Protection. A life member of the TorontoCentre, he has served as President, Secretary and Treasurer ofthat Centre, as well as National Newsletter Editor, National Treasurerand currently Assistant Editor with the Journal. An avid solareclipsechaser, he has observed 13 total and 2 annular eclipses,and is a contributor to the NASA Eclipse Bulletins. He receivedthe RASC Service Award Medal in 1999 and will mark 30 yearsas a member of the Society this fall.240 JRASCDecember/ décembre 2000

PHOTOELECTRIC MAGNITUDE MEASUREMENTSOF MARS MADE DURING THE 1998–2000APPARITIONby Richard W. Schmude, Jr.Kingston Centre, RASCGordon College, Barnesville, GAElectronic Mail: schmude@falcon.gdn.peachnet.edu(Received June 6, 2000; revised August 21, 2000)Abstract. An intense photoelectric magnitude study of Mars was carried out between 1998 and 2000. The selected normalizedmagnitudes for Mars in 1999 are: B(1,0) = -0.30 ± 0.02, V(1,0) = –1.60 ± 0.02, R(1,0) = –2.68 ± 0.03 and I(1,0) = –3.17 ± 0.03. The selectedsolar phase angle coefficients for Mars are: c B = 0.0185 ± 0.0010, c V = 0.0152 ± 0.0010, c R = 0.0110 ± 0.0010 and c I = 0.0109 ± 0.0010. In late1998 and early 1999, Mars was 0.04 magnitude brighter than was predicted in the Astronomical Almanac. The brightness and colourmeasurements of Mars are consistent with mid–summer being cloudier than mid–spring.Résumé. Une étude de la magnitude photoélectrique intense de Mars a été effectuée entre 1998 et 2000. Les magnitudes normaliséesde Mars sélectionnés en 1999 sont : B(1,0) = –0.30 ± 0.02, V(1,0) = –1.60 ± 0.02, R(1,0) = –2.68 ± 0.03 and I(1,0) = –3.17 ± 0.03. Les coefficientsde l’angle de la phase solaire sélectionnés pour Mars sont : c B = 0.0185 ± 0.0010, c V = 0.0152 ± 0.0010, c R = 0.0110 ± 0.0010 and c I = 0.0109± 0.0010. Vers la fin de 1998 et au début de 1999, Mars présentait une magnitude de 0.04 plus brillante que prévue à l’Almanac astronomique.Ces mesures de la brillance et de la couleur de Mars se conforment à une mi–été plus nuageuse que la mi–printemps.SEM1. IntroductionMars reached opposition on April 24, 1999 and attained an angularsize of 16 arc–seconds, which is the largest it has been since 1990. Byopposition day, most of the north polar cap had dissipated; it wasmid–summer (L s = 129°) in Mars’ northern hemisphere. In 1999, theMars Global Surveyor probe reached its mapping orbit and sent backhundreds of high resolution images of that planet. This probe alsomeasured the topography of Mars to an accuracy of 13 meters (Sky& Telescope 1999). Professional astronomers have found that watervapor was more abundant on Mars in 1999 than in previous years(McKim, 1999, BAA Circ. #5). Tom Clancy also reported that temperatureswere 5–10 Kelvins higher on Mars in early 1999 compared to 1997(McKim, 1999, BAA Circ. #5). Earth based observers noted twoMartian dust storms in late February and late March of 1999, bothoccurring near Vallis Marineris. Observers also noticed the gradualbrightening of Hellas, which peaked in February and March, andseveral equatorial cloud bands that were most frequent in Februaryand March. Both the Hubble Space Telescope and Earth-based observersrecorded a huge cyclone near 85°W, 65°N in late April; this storm hada diameter of 1500 km. These observations as well as others areexplained further elsewhere (McKim 1998–1999; Minami, 1998–1999).The author is planning to make photoelectric measurementsof Mars for another three oppositions, and this will cover all seasonsand latitudes for that planet. Brightness and color measurements willthen be compared to cloud and polar cap behavior. Finally this completeset of photometric data will yield better values for the geometric andbond albedos for all orientations of Mars and may improve globalclimate calculations for Mars. In this report the author summarizeshis photoelectric magnitude measurements of Mars, which weremade between Nov., 1998 and March 2000.2. MethodAn SSP–3 solid–state photoelectric photometer with filters transformedto the Johnson BVRI system were used in all measurements; thisinstrument is described elsewhere (Optec 1997; Schmude 1992). Thepeak wavelengths and half–maximum bandwidths for the filter–detectorsystems are: B–(420 nm and 100 nm), V–(540 nm and 85 nm), R–(700nm and 210 nm) and I–(860 nm and 220 nm). In all of the measurementsthrough September 5, 1999, a 0.51-metre Newtonian telescope wasused for the measurements. This instrument was stopped down toan aperture of 0.05 metres to prevent saturation of the detector.Characteristics of the comparison and check stars used in thephotoelectric measurements are summarized in Table I; Boo wasthe comparison star for all measurements between November 29,1998 and May 20, 1999. Although Boo is listed as a standard starin The Astronomical Almanac (1998), it is listed as a questionablevariable star in Hirshfeld et al. (1991) and as a variable star with anamplitude of less than 0.1 magnitude in Sinnott & Perryman (1997).Indeed, it appears that Boo is a variable star; however, the changein magnitude is less than 0.02 magnitude (Belmonte et al. 1990; Hatzes& Cochran, 1994). In fact, this star is probably a member of a newtype of low amplitude K–type variable star (Edmonds & Gilliland1996). The small variation in brightness of Boo is small and can beconsidered negligible. The average measured magnitude of the checkstar, Crv, are 4.33 ± 0.03, 2.98 ± 0.01, 2.02 ± 0.02 and 1.38 ± 0.03 forthe B, V, R and I filters, respectively. These measurements are closeto the literature values listed in Table I. The purpose of using a checkstar is to confirm the magnitude of the comparison star.All photometric measurements were corrected for both atmosphericextinction and transformed in the same way as is described in Halland Genet (1988). Transformation coefficients were measured usingthe two star method. The two stars used were Peg and Peg sincethese are listed as standard stars in The Astronomical Almanac (1998);December/ décembre 2000 Journal of the Royal Astronomical Society of Canada, 94: 241—245, 2000 December 241

the resulting transformation coefficients are: 0.091, –0.019, –0.072and –0.107 for the B, V, R and I filters, respectively. Each of these valueshas an estimated uncertainty of 0.01, and part of this uncertainty isdue to the slight variability of Peg (Sinnott & Perryman 1997).3. ResultsIndividual photoelectric magnitude measurements of Mars are listedin Table II. As in previous studies, Mars was broken up into 12 longituderanges. Normalized magnitudes at a solar phase angle , for eachfilter were calculated. The normalized magnitude of Mars for theV–filter was calculated from:V (1,) = -5.000 log [rd] + 2.5 log [k], (1)where V is the measured V–filter magnitude, r is the Mars–Earthdistance, d is the Mars–Sun distance and k is the fraction of Mars’disc that is illuminated by the Sun as seen from the Earth; both r andd are in astronomical units. Normalized magnitudes for the B, R andI filters were calculated in a similar way. The normalized magnitudefor each filter was then plotted against the solar phase angle () asin previous studies; there was a total of 48 graphs (four filters for 12longitude ranges); a sample graph is shown in figure 1. The data forB–V, V–R, and B–R colour indices. One trend in the data is that Marswas redder in the 1995 and 1997 apparitions compared to the 1999apparition. This colour change may be seasonal and due to the 1999measurements being made during a cloudy season on Mars. Beish &Parker (1988) report that the frequency of discrete clouds reaches apeak in early northern summer (L s = ~ 110°). Increased clouds willmake Mars both brighter and less red. Based on the cloud trendssummarized by Beish & Parker (1988) the author expects Mars to beredder and have a dimmer V(1,0) value in 2001, since the number ofclouds are expected to be lower.Photoelectric magnitude measurements were made on February22, 1999 at central meridians of 67°, 80° and 96°W, which were neara dust storm (McKim, BAA Circ. #4). The B–R colour indices, whenthe solar phase angle is taken into account, are about 0.05 magnitudehigher than expected, indicating that the dust made Mars a littleredder.Table V lists the difference between maximum and minimumbrightness at =0° for different filters during the last four apparitions.The major trend here is that the difference between the brightest anddimmest longitudes increases with increasing wavelength. This isconsistent with the fact that blue light photographs show less contrastthan red light photographs (Slipher 1962). Figure 2 is a plot of theFig. 2 — A plot of the measured B–R colour indices for solar phase anglesof 0, 18 and 36 degrees as a function of longitude for 1999.Fig. 1 — A plot of the normalized magnitude versus the solar phase angle.each graph were fitted to a least squares routine and both the slopeand y–intercept were evaluated. The slope is the solar phase anglecoefficient [c B , c V , c R and c I for the B, V, R and I filters] and the y–interceptis the normalized magnitude at a solar phase angle of 0°; the symbolsfor the normalized magnitude for = 0° in the B, V, R and I filters are:B(1,0), V(1,0), R(1,0) and I(1,0). Average values of the solar phase anglecoefficient and normalized magnitude for each filter were determinedfrom an equally weighted average of the values of all 12 longituderanges; the results are listed in Table III.4. DiscussionThe normalized magnitudes at a solar phase angle of 0°for the lastfour Mars apparitions are summarized in Table IV along with the1999 B–R colour indices at = 0°, 18° and 36° as a function of thelongitude of the central meridian. The figure shows that Mars isreddest at longitudes from 100°–220°W; furthermore the B–R colourindices changed by up to 0.3 magnitude (or about 30%) for differentlongitudes. It is therefore concluded that Mars’ colour changed by upto 30% as a function of longitude in 1999.The V–filter magnitude between November 29, 1998 and May20, 1999 are, on average, 0.04 magnitude brighter than the valueslisted in The Astronomical Almanac (1997, 1998). The discrepancywas even greater for the longitudes between 70° W and 220° W wheredifferences of 0.06 to 0.11 magnitude were observed. These observationsare consistent with the surface of Mars; essentially there are fewerdark areas in the northern hemisphere between 70° W and 220° Wthan at other longitudes, and so Mars should be brighter when thecentral meridian is between 70° W and 220° W longitude.242JRASCDecember/ décembre 2000

5. SummaryBesides the values in Table III, it is concluded that: 1) The normalizedmagnitude of Mars in the B, V, R and I filters became more negativebetween 1993 and 1999, 2) Mars became less red in 1999 probablybecause of more white Martian clouds as would be expected for theMartian season during which measurements were made, 3) Thedifference between the brightest and dimmest longitudes increasedfrom 0.19 magnitude in the B–filter to 0.39 magnitude in the I–filter,for the 1993–99 oppositions, 4) the B–R colour index changed by 0.3magnitude as Mars rotated in 1999, and 5) Mars was, on average, veryclose to predicted V–filter magnitude in the Astronomical Almanac.The author is planning to make photoelectric measurements of Marsfor another three oppositions, and this will cover all seasons andlatitudes for that planet. Brightness and colour measurements willthen be compared to cloud and polar cap behavior. Finally this completeset of photometric data will yield better values for the geometric andbond albedos for all orientations of Mars and may improve globalclimate calculations for Mars.AcknowledgementsThe author would like to thank Elizabeth Waagen for carrying out aSINBAD search for Boo. The author is also grateful to the AtlantaAstronomy Club for maintaining the facilities at the Walter BarberObservatory.Richard W. Schmude, JR.Gordon College419 College DriveBarnesville, Georgia, 30204ReferencesAstronomical Almanac for the Year 1998, The 1997, U. S. Government PrintingOffice, Washington D.C.Astronomical Almanac for the Year 1999, The 1998, U. S. Government PrintingOffice, Washington D.C.Beish J. D. & Parker, D. C. 1988, Sky & Telescope, 75, No. 4, 370Belmonte, J. A., Jones, A. R., Pallé, P. L. & Cortés, T. R. 1990, Astrophys. J. 358,595Edmonds, P. D. & Gilliland, R. L. 1996, Astrophys. J. 464, L157Hall, D. S. & Genet, R. M. 1988, Photoelectric Photometry of Variable Stars,second edition (Willmann–Bell: Richmond)Hatzes, A. P. & Cochran, W. D. 1994, Astrophys. J. 422, 366Hirshfeld, A., Sinnott, R. W. & Ochsenbein F. 1991, Sky Catalogue 2000.0, Vol.1, second edition (Sky Publishing: Cambridge)Iriarte, B., Johnson, H. L., Mitchell, R. I. & Wisniewski, W. K. 1965, Sky &Telescope, 30, No. 1, 21McKim, R. 1998–1999, British Astronomical Association Mars Circulars(Nos. 1–6)Minami, M. 1998–1999, Communications in Mars Observations, publishedby the Oriental Astronomical Society (Nos. 208–219)Optec Inc. 1997, Model SSP–3 Solid–State Stellar Photometer TechnicalManual for Theory of Operation and Operating Procedures (OptecInc: Lowell, MI)Schmude, R. W. Jr. 1992, J. Assoc. Lunar & Planet. Obs. 36, 20Schmude, R. W. Jr. & Bruton, D. 1994, Journal Roy. Astron. Soc. Can. 88, 69Schmude, R. W. Jr. 1996, Journal Roy. Astron. Soc. Can. 90, 193Schmude, R. W. Jr. 1998, Journal Roy. Astron. Soc. Can. 92, 190Sinnott, R. W. & Perryman, M. A. C. 1997, Millennium Star Atlas(Sky Publishing: Cambridge)Sky & Telescope, 98, No. 3, 22 (1999)Slipher, E. C. 1962, The Photographic Story of Mars (Sky Publishing: Cambridge)Table IComparison and check stars used in the photoelectric magnitude study of Mars in 1999.All right ascensions and declinations are from Hirshfeld et al. (1991) andall magnitudes are from Iriarte et al. (1965)Star Right Ascension Declination MagnitudeB V R I Boo 14 h 16 m 19° 11 m 1.18 -0.06 –1.04 –1.70 Crv 12 h 10 m –22° 37 m 4.32 2.98 2.05 1.40 Sco* 16 h 00 m –22° 37 m 2.23 2.33 ––– ––– Cyg* 20 h 22 m 40° 15 m 2.90 2.23 ––– ––– And* 00 h 08 m 29° 05 m 1.95 2.06 ––– –––*These were the comparison stars for the September 5, 1999, January 16, 2000 and March5, 2000 V–filter measurements and so R and I magnitudes were not used and are not listed.The B–filter magnitudes of these stars were used in the transformation corrections.December / décembre 2000 JRASC243

Table IIPhotoelectric Magnitude Measurements of Mars made in 1998–2000Date (U.T.) Central L s Solar Phase Magnitude(°W) Meridian (deg.) Angle (deg.) B V R I1998Nov. 29.385 198 63 32.7 2.80 1.39 0.15 –0.34Nov. 29.421 211 63 32.7 2.81 1.41 0.18 –0.30Nov. 29.447 220 63 32.7 2.81 1.42 0.19 –0.31Nov. 29.475 229 63 32.7 2.81 1.43 0.21 –0.27Nov. 29.496 237 63 32.7 2.78 1.43 0.21 –0.261999Jan. 11.335 126 82 36.2 2.47 0.91 –0.45 –0.99Jan. 11.345 130 82 36.2 2.44 0.89 –0.42 –0.98Jan. 11.379 142 82 36.2 2.36 0.87 –0.45 –0.99Jan. 11.424 157 82 36.2 2.32 0.87 –0.43 –0.97Jan. 11.459 170 82 36.2 2.33 0.88 –0.42 –0.95Jan. 11.467 172 82 36.2 2.34 0.88 –0.41 –0.93Jan. 25.340 354 88 36.2 2.00 0.63 –0.53 –1.01Jan. 25.377 8 88 36.2 2.00 0.65 –0.51 –0.98Jan. 25.428 26 88 36.2 1.98 0.65 –0.54 –1.02Jan. 25.450 33 88 36.2 1.97 0.62 –0.57 –1.03Jan. 25.479 43 88 36.2 1.95 0.60 –0.58 –1.05Feb. 5.307 239 93 35.6 1.77 0.35 –0.78 –1.23Feb. 5.347 253 93 35.6 1.79 0.41 –0.77 –1.23Feb. 5.373 262 93 35.6 1.80 0.42 –0.77 –1.23Feb. 5.422 279 93 35.6 1.79 0.40 –0.79 –1.25Feb. 5.434 283 93 35.6 1.79 0.41 –0.79 –1.26Feb. 5.458 291 93 35.6 1.79 0.41 –0.80 –1.26Feb. 5.478 299 93 35.6 1.80 0.40 –0.80 –1.27Feb. 22.268 67 101 33.3 1.36 0.01 –1.30 –1.80Feb. 22.310 80 101 33.3 1.39 –0.03 –1.32 –1.83Feb. 22.358 96 101 33.3 1.36 –0.05 –1.36 –1.89March 4.258 329 105 31.9 1.20 –0.26 –1.36 –1.82March 4.285 338 105 31.9 1.18 –0.24 –1.37 –1.85March 4.324 352 105 31.9 1.19 –0.20 –1.36 –1.82April 2.180 38 118 17.4 0.12 –1.15 –2.22 –2.75April 2.202 45 118 17.4 0.13 –1.15 –2.24 –2.75April 2.225 53 118 17.4 0.16 –1.14 –2.27 –2.76April 2.269 69 118 17.3 0.17 –1.16 –2.34 –2.81April 2.283 74 118 17.3 0.16 –1.18 –2.35 –2.80April 12.160 302 123 10.4 –0.24 –1.50 –2.64 –3.08April 12.258 336 123 10.3 –0.08 –1.43 –2.56 –3.00April 12.293 349 123 10.3 –0.17 –1.46 –2.56 –3.02April 12.302 352 123 10.3 –0.15 –1.45 –2.57 –3.03April 18.224 271 126 5.5 –0.20 –1.58 –2.64 –3.13April 18.246 279 126 5.5 –0.28 –1.60 –2.64 –3.12April 18.272 288 126 5.5 –0.29 –1.62 –2.67 –3.15April 18.327 308 126 5.4 –0.24 –1.55 –2.66 –3.15April 18.360 319 126 5.4 –0.22 –1.57 –2.67 –3.16April 18.396 332 126 5.4 –0.23 –1.63 –2.64 –3.18April 19.123 227 126 4.8 –0.41 –1.73 –2.88 –3.39April 19.145 235 126 4.8 –0.35 –1.66 –2.83 –3.29April 19.179 247 126 4.8 –0.37 –1.67 –2.79 –3.28May 1.290 181 132 5.7 –0.38 –1.62 –2.78 –3.32May 2.104 108 133 6.4 –0.38 –1.75 –2.94 –3.46May 2.129 116 133 6.4 –0.41 –1.74 –2.94 –3.42244JRASC December / décembre 2000

May 2.147 122 133 6.4 –0.44 –1.76 –2.94 –3.46May 2.201 142 133 6.5 –0.40 –1.76 –2.95 –3.46May 2.220 148 133 6.5 –0.36 –1.76 –2.95 –3.45May 2.252 159 133 6.5 –0.38 –1.77 –2.94 –3.42May 2.271 166 133 6.5 –0.38 –1.76 –2.95 –3.42May 2.317 183 133 6.6 –0.40 –1.76 –2.91 –3.43May 2.344 191 133 6.6 –0.47 –1.80 –2.97 –3.49May 2.361 197 133 6.6 –0.34 –1.77 –2.94 –3.46May 9.082 38 136 12.2 –0.24 –1.49 –2.55 –3.01May 9.103 45 136 12.2 –0.27 –1.51 –2.58 –3.03May 9.229 88 136 12.3 –0.31 –1.62 –2.74 –3.25May 9.265 102 136 12.3 –0.38 –1.69 –2.79 –3.34May 20.082 300 141 20.5 0.05 –1.25 –2.42 –2.89May 20.107 309 141 20.5 0.06 –1.24 –2.43 –2.91May 20.141 321 141 20.5 0.11 –1.22 –2.43 –2.92May 20.167 330 141 20.5 0.09 –1.23 –2.42 –2.90May 20.201 342 142 20.5 0.06 –1.25 –2.42 –2.86May 20.224 350 142 20.6 0.09 –1.25 –2.41 –2.88Sep. 5.062 a 353 200 44.0 ––– 0.59 ––– –––2000Jan. 16.015 a 111 283 29.2 ––– 0.99 ––– –––March 5.043 a 352 313 21.2 ––– 1.18 ––– –––a The comparison star on the September 5 measurement was Sco; the comparison star forthe January 16 measurement was Cyg while And was the comparison star for the March5 measurement. The September 5, January 16 and March 5 measurements were made whenMars was at low elevations and were not used in computing the values in Table 3.Table IIISelected normalized magnitudes and solar phase angle coefficientsfor Mars in 1998-2000Filter Normalized Solar Phase Angle Mean ApparitionMagnitude Coefficient (mag/deg) MagnitudeB –0.30 ± 0.02 0.0185 ± 0.0010 –0.79 ± 0.02V –1.60 ± 0.02 0.0152 ± 0.0010 –2.09 ± 0.02R –2.68 ± 0.03 0.0110 ± 0.0010 –3.17 ± 0.03I –3.17 ± 0.03 0.0109 ± 0.0010 –3.66 ± 0.03Table IVNormalized magnitudes and colour indices for Mars during the 1993-99apparitions. The solar phase angle of Mars equals zero degrees for allvalues; data are from Schmude & Bruton (1994) and Schmude (1996, 1998)Apparition B (1,0) V (1,0) R (1,0) I (1,0) B–V V–R B–R1993 –0.23 –1.49 –2.60 –3.01 1.26 1.11 2.371995 –0.20 –1.54 –2.67 –3.14 1.34 1.13 2.471997 –0.26 –1.58 –2.72 –3.16 1.32 1.14 2.461999 –0.30 –1.60 –2.68 –3.17 1.30 1.08 2.38Table VDifference between maximum and minimum brightness of Mars as thatplanet rotates on its axis for different filters and in different years at = 0°Apparition B-filter V-filter R-filter I-filter1992–93 0.18 0.21 0.31 0.391994–95 0.21 0.19 0.23 0.421996–97 0.17 0.24 0.25 0.311998–99 0.20 0.24 0.40 0.44Average 0.19 0.22 0.30 0.39RICHARD W. SCHMUDE, Jr. grew up in Houston, Texas andgraduated from Texas A&M University in 1994 with a Ph.D degreein Chemistry under the guidance of Dr. Karl Gingerich. Since 1994,Richard has taught Chemistry, Astronomy and Physical Scienceat Gordon College in Barnesville, GA. He has attended GA’s inWindsor, Kingston, Toronto and Winnipeg, Canada. He has givenover 150 professional and community talks about Astronomy andChemistry. He is a member of the American Association of VariableStar Observers, The Association of Lunar and Planetary Observers,The Atlanta Astronomy Club, The Flint River Astronomy Club andthe Kingston Centre of the Royal Astronomical Society of Canada.December / décembre 2000 JRASC245

ABSTRACTS OF PAPERS PRESENTED AT THE 2000 CASCAANNUAL MEETING HELD IN VANCOUVER, MAY 25-28, 2000J.S. Plaskett Medal Lecture/Conférence de la médaille J.S. Plaskett3D Radiative Transfer to Compute the Inhomogeneous Reionization,Alexei Razoumov, University of California, San DiegoA numerical scheme for the solution of the three-dimensional, frequencyand time dependent radiative transfer equation with variable opticaldepth is developed for modelling the reionization of the Universe. Untilnow, the main difficulty in simulating the inhomogeneous reionizationhas been the treatment of cosmological radiative transfer. The proposedapproach is drastically different from previous studies, which eitherresorted to a very simplified, parametric treatment of radiative transferor relied on one-dimensional models. The algorithm presented hereis based on explicit multidimensional advection of wavefronts at thespeed of light, combined with the implicit solution of the local chemicalrate equations separately at each point. We have shown that this methodis an attractive choice for simulation of astrophysical ionization fronts,particularly when one is interested in covering a wide range of opticaldepths within a 3D clumpy medium. This scheme is then applied tothe calculation of time-dependent, multi-frequency radiative transferduring the epoch of first object formation in the Universe. In a seriesof models, the 2.5 Mpc (comoving) simulation volume is evolved betweenthe redshifts of z = 15 and 10 for different scenarios of star formationand quasar activity. The current numerical resolution is 128 3 (spatial)× 10 2 (angular) × 3 (frequency), and at each point in space we calculatevarious stages of hydrogen and helium ionization accounting for ninechemical species altogether. These models can be used to predict theobservational signatures of the earliest astrophysical objects in theUniverse. At present, the calculations are accurate enough to resolveprimordial objects to the scale typical of globular clusters, 1 × 10 6 solarmasses.Contributed Papers/Présentations oralesUnveiling Dwarf Galaxies in Low Redshift Galaxy Clusters, W. A. Barkhouseand H. K. C. Yee, University of Toronto, and O. López-Cruz, InstitutoNacional de Astrofísica Óptica y Electrónica, MexicoWe have recently completed a comprehensive photometric survey of27 Abell clusters (0.02 < z < 0.04) with the 8k mosaic camera on theKPNO 0.9-m telescope. The dwarf galaxy population has been characterizedby constructing luminosity functions, measuring spatial variations,dwarf-to-giant galaxy ratios, and colour distributions. Preliminaryresults for several galaxy clusters will be presented.The Magnetic Field Configuration in the Outer Region of the Galaxy, J.C.Brown and A.R. Taylor, University of CalgarySeveral studies have demonstrated that the Galaxy has a magneticfield with an ordered large-scale structure. We do not, however, knowhow that field is generated, how it is evolving, or what its overall structureis. It is generally believed that the magnetic field follows the basicpattern of the spiral arms of the Galaxy, yet the field’s strength anddirection between and within the arms is unknown. Different theoreticalmodels of the generation and evolution of the magnetic field predictdifferent directions. Studying the magnetic field and looking for“reversals,” where the field’s direction changes by 180 degrees, will helpidentify which model is correct. The focus of our research is to userotation measures from extragalactic point sources in the CanadianGalactic Plane Survey (CGPS), in conjunction with established datafrom pulsars to infer information about the Galaxy’s magnetic field.In particular, we hope to resolve the debate over how many (if any)reversals are present in the outer region of the Galaxy. In our paper, wewill discuss the status of our work to address this question and presenta comparison between measured rotation measures and those calculatedfrom different magnetic field models of the outer Galaxy.H ii Region NRAO 655 and its ISM Environment, T. Foster and D. Routledge,University of AlbertaNew radio and optical observations of Galactic surroundings near (l,b) = (94°, 2°) are presented, revealing new information about theinterstellar medium and objects in this locale. Of eleven Galactic objectsin this neighbourhood, for example, only two have published distanceestimates. In this paper, we present new CGPS radio continuumobservations of the H ii region NRAO 655 (G93.4 + 1.8) at 21 cm and74 cm, and optical and radio emission line observations at 656 nm and21 cm. The radio spectrum of this object confirms its emission asthermal in origin. From the CGPS H i data we find an atomic hydrogencavity associated with this object at v = –71.5 km s –1 . This H i cavitycorresponds in position and size to the brightest radio continuumemission from NRAO 655. The corresponding kinematic distance is8.8 kpc, and NRAO 655’s linear size is therefore 70 pc × 130 pc. Toconfirm the ( = 21 cm) H i velocity we present the first recombinationline detection of NRAO 655 H158 () line, v = –72 km s –1 , width 40 kms -1 , and the first observations of a molecular cloud interacting withNRAO 655 (at –72 km s –1 ). The first detection of NRAO 655 in (H)emission line is also presented, and astrophysical properties aredetermined from the nebula’s (H) emission line luminosity. We findgood correlation between optical and radio morphology and betweenIRAS 60 m infrared and radio morphology. We find anti-correlationbetween optical and infrared features, suggesting absorption of (H)light emitted from NRAO 655 by dust present in the nebula. A physicalmodel for NRAO 655 and its environment is proposed.Sub-millimetre Polarimetry of Star Forming Regions in Orion B, GeraldH. Moriarty-Schieven, National Research Council, Joint AstronomyCentre, Brenda Matthews, McMaster University, and Jason Fiege,Canadian Institute of Theoretical AstrophysicsPolarimetry of sub-millimetre dust emission allows one to trace thestructure of magnetic fields perpendicular to the line-of-sight. Wepresent polarimetric images, obtained with the SCUBA polarimeter246Journal of the Royal Astronomical Society of Canada, 94: 246—251, 2000 DecemberDecember / décembre 2000

at the James Clerk Maxwell Telescope, of three star forming regionswithin the Orion B molecular cloud. NGC 2024 contains a string oflow- to intermediate-mass protostars embedded within a filamentaryridge, much like beads on a string. Percentage polarization is verysmall (< 2%) toward the ridge and increases away from the ridge to> 5%. The polarization is very ordered as well, with vectors along theridge mostly parallel to the ridge, while vectors to the east and west ofthe ridge are oriented roughly +45° and –45° respectively with respectto the ridge. NGC 2071 IR contains a cluster of protostars dominatedby a 15 solar mass YSO which drives a massive bipolar outflow. Towardthe emission peak the polarization is very weak (< 1%), increasing awayfrom the peak. The vector orientations are perpendicular to each othertoward the north-east and south-west (i.e., the orientation of themolecular outflow). The third region, LBS23 (HH 24-26) forms a chainof mostly isolated peaks. Here the polarization is very ordered, exhibitinga distinct change of direction in the south. These regions show polarizationpatterns which cannot be interpreted as due to uniform magneticfields. One model which fits the data is that of a helical magnetic fieldinclined to the line-of-sight. This work is part of the Canadian Consortiumfor Star Formation Studies.What MOST Can Tell Us about the Close-in Extrasolar Giant Planets,Sara Seager, Institute for Advanced Study, Princeton UniversityThe discovery of 51 Peg b in 1995, only 0.05 AU from its parent star,heralded an unexpected, new class of planets. The recent transitdetection of HD209458 b confirms that this class of extrasolar giantplanets (CEGPs) — now with several members — are gas giants. Seventimes closer to their parent stars than Mercury is to our Sun, the CEGPsare potentially bright in reflected light. With the ability to detectmicromagnitude photometric variation, MOST will be able to observethe reflected light curves of the planet in the combined star + planetlight. For a transiting planet, MOST may be able to detect moons andplanetary rings (if they exist) as they occult the stellar disk. I will presentresults of theoretical computations, and discuss what can be inferredfrom MOST observations of a star with an orbiting CEGP.The Chandra Observatory — Overview, Capabilities, Scientific Results,and Status, Martin Zombeck, Harvard-Smithsonian Center forAstrophysicsOn July 23 rd , 1999 the Chandra X-ray Observatory (CXO) was launchedby NASA’s Space Shuttle Columbia. The first celestial X-rays wereobserved on August 12 th , 1999. Since then, after an initial on-orbitactivation and calibration phase, the observing program was initiated.An overview of the Chandra X-ray Observatory will be presented alongwith its capabilities for high spatial resolution imaging and highresolution spectroscopy. Examples of a variety of initial and recentobservations will be presented to highlight the observatory’s capabilitiesand the level of science that can be done. The present status of theobservatory and the observing program will be presented.Poster Papers/Présentations “Posters”Hopkins University/University of Victoria, R. G. Ohl and H. W. Moos,Johns Hopkins UniversityHigh-dispersion observations of the far-ultraviolet (FUV) spectrumof the subdwarf B star PG 0749+658 (T eff = 24,600 K and log g = 5.5)reveal the presence of many photospheric and interstellar lines. Thespectrum, obtained by the Far Ultraviolet Spectroscopic Explorer (FUSE),has a resolution of about R = 12000–15000 and covers a wavelengthrange of 905–1187 Å. We determine C, N, Si, P, S, Cr, Mn, Fe, and Niabundances, and upper limits on the abundance of Cl and V, using agrid of synthetic spectra based on a LTE stellar atmosphere model.Abundance anomalies are observed in the atmosphere of this sdB star.He, C, N, Si, and Cl are depleted by a factor greater than 10 with respectto solar, while P, S, and Fe are diminished by less than a factor of 10.We measure a solar abundance of Cr and Mn, and a Ni enhancementof about 0.6 dex. We compute the predicted abundances within theframework of the equilibrium radiative levitation theory and comparethem to the atmospheric observed abundances. The measured abundancesare generally consistent with predictions based on the equilibriumradiative theory, except for He and Si. The under-abundances of Heand Si are not explained by this theory alone.A Side-band Separating Balanced Mixer for ALMA, Stephane Claude,Charles Cunningham, Jerry Sebesta, Luc Martin, and Lorne Avery,Herzberg Institute of Astrophysics, National Research CouncilCurrent millimetre and sub-millimetre radio receivers generally relyon simple heterodyne mixers to down-convert the signal to the lowerintermediate frequency. In this process the output of the mixer containsinformation received in both the upper and lower side-bands. Thisdegrades the receiver performance as noise from the sky enters theunused side-band. Also, it can result in confusion as lines appearingin the spectra could have been received in either side-band. If offered,side-band separation is usually provided by a tuneable interferometerthat terminates the unwanted side-band on a cold load. The AtacamaLarge Millimetre Array (ALMA) will have 64 antennas, each requiringreceivers that cover 10 separate frequency bands. It is clear that for thisproject, interferometers cannot be used due to cost, size, and reliabilityconsiderations. In this paper we describe a mixer design that separatesthe side-bands internally and does so over a broad RF bandwidth. Themixer is physically very compact and has no moving parts. In addition,the mixer is balanced and as a result offers a very efficient mean oflocal oscillator injection. This is especially important for the ALMAproject where local oscillator power is required over large bandwidthsat high frequencies. The mixer is a split waveguide design. One inphasepower splitter divides the input signal and a 90 degree out ofphase 3 dB hybrid coupler splits the local oscillator signal. After beingcombined using two 90 degree 3 dB hybrid couplers the signal and thelocal oscillator are injected into two balanced mixers. After downconversion,the IF signal is separated into upper and lower side-bandsusing a micro-strip 90 degree 3 dB hybrid coupler.Counting All the Stars, P. A. Delaney, York University, and R. M. Robb,University of VictoriaFUSE Observations of the Subdwarf B Star PG 0749+658, P. Chayer, JohnsDecember / décembre 2000 247JRASC

With the increasing availability of inexpensive CCD cameras and theimproving situation with computer-IRAF resources, a new laboratoryexercise has been developed that exposes students to a variety ofinteresting and useful astronomical concepts. Assuming a homogeneousdistribution of stars and no interstellar extinction, a plot of the logarithmof the number of stars as a function of magnitude will have a slope of0.6. The students use a SBIG ST-8 (or comparable) CCD camera witha 28-mm lens to obtain a wide field 10 second exposure of the nightsky. After downloading this image into IRAF, DAOFIND is used to dothe photometry to illustrate the relationship between the magnitudeof the stars and the number of stars visible. When the students comparetheir results to the expected slope of 0.6, they find that it is significantlysmaller. Discussion of this discrepancy illuminates the error in theassumptions. The same data can be used to crudely establish the centrallocation of a cluster of stars. This exercise is useful at the first-or-secondyearastronomy undergraduate level.Diffuse Molecular Gas in the Milky Way, K. A. Douglas and A. R. Taylor,University of CalgaryObservations of the gas and dust content of high-latitude gas cloudshave shown interesting relationships between the emission by thedifferent constituents of these structures. Several studies comparingIRAS, H i and CO emission in these cirrus clouds have yielded evidenceof a molecular component which is not traced by the emission of COmolecules (Reach et al. 1994, ApJ, 429, 672; Meyerdierks & Heithausen1996, AA, 313, 929; Boulanger et al. 1998, AA, 332, 273). Infrared excessemission from IRAS data points to the possibility of a molecular gascomponent that is warmer and more diffuse than the component ofmolecular gas that is traceable by CO. In these studies, the “diffuse”component of molecular hydrogen is found to be comparable in massto the H i content. This diffuse gas may be widely abundant in theplane of the Galaxy. If present, on the same scales as in these highlatitude clouds, it has important implications for many areas ofastrophysical interest. The Canadian Galactic Plane Survey (CGPS)offers an excellent opportunity to study the phenomenon of diffusemolecular gas in the plane of the Galaxy by combined analysis of pcscaleresolution images of CO, H i and dust emission over a large areaof the Galactic disk.A FUSE Survey of O vi in the Winds of LMC O Stars, A. W. Fullerton,University of Victoria/Johns Hopkins University, D. L. Massa, RaytheonITSS, and J. B. Hutchings, DAO/HIA/NRCHigh-resolution FUSE spectra of stellar wind profiles in the O viresonance doublet are presented for a sample of O stars in the LargeMagellanic Cloud. This transition is the best diagnostic of high-energyprocesses in the optical/UV range. It is present in the winds of all thestars in the sample, which cover spectral classes from O3 to B0.5 withemphasis on luminosity classes I–III. The strength and morphologyof the P Cygni profiles change systematically along the temperaturesequence: early types exhibit pronounced emission lobes, while latertypes show weaker emission but comparatively strong absorption athigh velocity. This morphology suggests that the distribution of O viions is concentrated towards larger wind velocities, particularly for thelater spectral types. Work is underway to quantify this distribution, inorder to constrain the properties of the ensembles of embedded shocksthat are the likely production mechanism for O vi.Revisiting the Classics, R.F. Garrison, Christopher Capobianco andCristina Fayet, David Dunlap Observatory, University of TorontoThe set of classical shell stars studied by Gulliver in the mid-1970s andby Merrill in the 1930s, 40s and 50s has been re-observed. The observationsand reductions were carried out by two undergraduate students aspart of a second-year, Research Opportunities Program at the Universityof Toronto. Shell stars have a wide variety of characteristics, which varyunpredictably, but with a characteristic timescale of the order of decades.A great deal can be learned by occasional monitoring of their spectra.This has not been done systematically since Gulliver’s work. The 1.88-m telescope of the David Dunlap Observatory was used with theCassegrain spectrograph and 1024 × 1024 CCD. The resulting twopixelresolution is about one angstrom. Description of the current shellcharacteristics is given.The Karma Astronomical Visualisation Software, R. Gooch, Universityof CalgaryModern astronomical instruments are producing larger and largerquantities of data. New techniques are required to visualise and analysethese data. This poster discusses the Karma visualisation software(available for free down-load from http://www.atnf.csiro.au/karma/), which addresses these needs. The Karma visualisationsoftware contains a set of programming libraries which provide acommon infrastructure for a suite of visualisation tools. This designeases development of new visualisation tools and results in tools witha common user interface. A few features of this package are: supportfor a large variety of data formats, such as FITS, Miriad, GIPSY, DRAO,AIPS, AIPS++, Starlink and common image formats such as PPM, GIF,TIFF and so on, support for compressed data files and sub-samplingupon read support for astronomical co-ordinate systems (conventionalFITS-style and DSS projections), including the ability to overlay imageswith different projections, pixel scales and rotations, linear, squarerootand logarithmic intensity transformations, output PostScript andPPM for publication and output of FITS, Miriad and GIPSY for subsampledor computed datasets, axis labelling and user control ofannotations, fully interactive zooming, panning and magnification,built-in analysis features (spectral, summed and radial profiles, Gaussianfitting, image statistics, moment maps, etc.) and much, much more.Karma comes with many specialised visualisation tools, some of whichare displayed in this poster.BD+61 2213: An Early-type Binary System in the Open Cluster NGC 7160,D. E. Holmgren, Brandon University, and A. E. Tarasov, CrimeanAstrophysical ObservatoryNew spectral data and orbital parameters are presented for the shortperiod(P = 1.2 d) B3 binary system BD+61 2213. This star is a memberof the open cluster NGC 7160. On the basis of a spectroscopic orbitand component line profiles (He i 6678 Å and H) recovered from aspectral disentangling solution, we find primary and secondary minimum248JRASC December / décembre 2000

masses of 4.3 and 3.2 solar masses respectively. As the system is knownto be non-eclipsing, we find a maximum orbital inclination of 53 degrees,which implies that the masses must be at least 8.5 (primary) and 6.2(secondary) solar masses. From measures of the equivalent width ofthe component He i 6678 Å profiles and comparisons of these datawith non-LTE model atmosphere calculations, we conclude that bothstars are slightly evolved.The CFHT Open Star Cluster Survey: CCD Photometry of NGC 2099,Jasonjot Singh Kalirai, Harvey B. Richer, Patrick R. Durrell, and GregoryG. Fahlman, University of British Columbia, Gianni Marconi andFrancesca D’Antona, Osservatorio Astronomico di RomaWe will present preliminary CCD photometric results for the open starcluster NGC 2099 (M37). NGC 2099 is the first of 19 carefully selectedopen clusters in a survey which was taken using the CFH12k CCDcamera. This is the largest close-packed CCD currently being used forastronomical research. The goals of this survey are to identify a largecollection of white dwarf stars (approximately 100) and to producethe first major observational tests for the theoretical models availablefor the white dwarf initial-final mass relationship. The colour-magnitudediagram of NGC 2099 shows that it contains a very rich stellar populationand one of the longest (10 magnitudes) and most tightly constrainedmain sequences ever established for open star clusters. The CMD isalso deep enough (V = 24) to reveal about a half dozen white dwarfcandidates. Additionally, there is an excellent agreement between thetheoretical isochrones and the data for the main sequence of the cluster.Consequently, our derivations of cluster parameters, such as age anddistance, have refined previous values significantly.The Canadian Galactic Plane Survey: Exploring the Interstellar MediumUsing Radio Polarimetry, T. L. Landecker, P. E. Dewdney, A. D. Gray, andB. Uyanıker, National Research Council, Herzberg Institute of Astrophysics,Dominion Radio Astrophysical Observatory, J.C. Brown and A. R. Taylor,University of Calgary, and M. Peracaula, Universitat de BarcelonaThe DRAO Synthesis Telescope is imaging a large part of the plane ofthe Milky Way as part of the Canadian Galactic Plane Survey, producingfull polarization images of the continuum emission at 1420 MHz inaddition to other data products. Widespread polarization structureis seen which has no corresponding variation in the total power of theemission. Because the effect is seen predominantly in polarizationangle, it is interpreted as arising from irregular Faraday rotation in anintervening magneto-ionic medium (MIM), ionized gas threaded bymagnetic fields. We refer to this as the Faraday screen. The state ofthe polarization when the signal arrives at the telescope tells moreabout the MIM through which the signal has passed than it tells aboutthe source of the emission itself, the Galactic synchrotron emission,linearly polarized at the point of origin. Faraday rotation cannot destroypolarization, but rapidly varying Faraday rotation (for example in adense, turbulent H ii region) can reduce the apparent degree ofpolarization by vector averaging across the beam or the reception bandof the telescope. Such effects are loosely referred to as “depolarization,”and can be used to derive astrophysically useful information. Supernovaremnants are polarized emitters, but at 1420 MHz their polarizationdoes not stand out. Rather, the dominant feature in the images is theFaraday screen itself. This paper illustrates the use of polarimetry toexplore physical conditions in the ISM.On the Power-Law Relation between the Scalar Field and the CosmicExpansion Factor in Brans-Dicke Theory, S. O. Mendes, M. N. Butler,and M. J. West, Saint Mary’s UniversityWe explore cosmological models in the context of Brans-Dicke theory.It is shown that a power-law relationship between the scale factor andthe scalar field might be obtained in order to recover the Brans-Dickeexpression for the effective gravitational constant. Furthermore, theexponent of such power-law relation is shown to constrain the couplingparameter Ω of the theory in a very specific way.A Further Improved Light Curve Modeling Package: WD98, E.F. Milone,C. R. Stagg, and M.D. Williams, University of Calgary, J. Kallrath (BASF),Dirk Terrell (SwRI), and W. Van Hamme (FIU)A guiding motivation for the development of efficient light curvemodeling code is the opportunity to obtain fundamental stellar datafrom analyses of eclipsing binary light curves in the local field as wellas in open and globular clusters. Previously we developed a self-iterating,damped least-squares light curve modeling program that was builtaround the Wilson-Devinney code of ~1993, but augmented by R. L.Kurucz’s atmosphere models: WD95. (See Kallrath & Milone, EclipsingBinary Stars: Modeling & Analysis, Springer, 1999, for a thoroughdiscussion of the philosophy and practical considerations that led tothis code). Meanwhile, R. E. Wilson further developed the basic code,replacing his least-squares engine, and expanding the treatment ofreflection, limb-darkening, and adding treatment of local scatteringeffects. We have now applied all our previous improvements to thisnew WD version; we call the package WD98. In addition, this versioncan automatically generate a parameter grid with sequential variationsof a certain parameter, e.g., the mass ratio. This work has been supportedby NSERC and the University of Calgary Research Grants Committeethrough grants to EFM.IRMA: An Infrared Radiometer for the Correction of Phase Errors inSubmillimetre Astronomical Interferometry, D. A. Naylor and G. J. Smith,University of Lethbridge, and P. A. Feldman, Herzberg Institute ofAstrophysicsThe performance of existing and planned millimetre and submillimetreastronomical arrays is limited by fluctuations in the amount ofatmospheric water vapour along the antenna’s line of sight. Correctingthe resulting phase distortion of the received signals is seen as asignificant technological challenge. Measurements of the variation inthe line-of-sight water vapour abundance at the level of 1 micronprecipitable water vapour on a time scale of 1 second and at arbitraryantenna positions are required. In this paper we will present the designof, and preliminary results obtained with, a water vapour monitoroperating at infrared wavelengths which shows considerable promisefor this application. Improvements in, and future plans for, the secondgeneration water vapour monitor currently under development willbe discussed.December / décembre 2000 JRASC249

VLBI Imaging of the Gravity Probe-B Guide Star HR 8703, R. R. Ransom,N. Bartel and M. F. Bietenholz, York University, D. E. Lebach, M. I. Ratnerand I. I. Shapiro , CfA, and J.-F. Lestrade, Observatoire de Paris-MeudonMulti-epoch VLBI observations at 3.6 cm have been made of the RSCVn binary star HR 8703 (IM Pegasi) in support of the NASA-Stanfordrelativity gyroscope experiment, Gravity Probe B (GP-B). We presentphase-referenced maps of HR 8703 produced from thirteen sets ofobservations between January 1997 and December 1999. The mapsreveal a variety of radio emission structures. Maps from temporalsubsets of several observing sessions show both structural evolutionin the stellar radio emission and sub-milliarcsecond motion of theradio brightness peak on hour time scales. We discuss what we havelearned so far about the underlying processes responsible for theobserved radio emission in HR 8703, and examine the implications ofour astrometric results for the GP-B experiment.Activity Related to Star Formation Associated with G79.3+0.3, R. O.Redman, NRC/HIA, D. D. Balam, University of Victoria, P. A. Feldman,NRC/HIA and S. J. Carey, Boston CollegeWe have employed several telescopes in a multi-wavelength study ofstar forming activity in and around the nearby Infrared-Dark Cloud(IRDC) G79.3+0.3. The Midcourse Space Experiment (MSX) providedimages of the region at 8 m. The JCMT was employed with SCUBAto image the region at 850 and 450 m, and with RxA3 to map thetransitions of 13 CO (2-1) and C 18 O (2-1). The NRC’s 1.82-m PlaskettTelescope was used to image the region with various optical and IRfilters, including the transitions of H , [S ii] at 6716/6731Å, [Fe ii]at 1.64 m, the S (1) line of H 2 (v = 1-0) at 2.12 m, and a narrow-bandCO filter at 2.30 m. The SCUBA images reveal a variety of objects inthe early stages of star formation, including a Class-0 protostar andanother protostar showing evidence of infalling gas. All of the bright,compact sources in the SCUBA images have line wings indicative ofoutflow. Magnetic fields inferred from the polarization images appearwell-ordered and aligned with structures in the maps of dust and gas.The images made with the Plaskett Telescope have revealed the presenceof one or two Herbig-Haro (HH) jets. The source of the strongest jetappears to be a T Tauri-like star embedded in an edge-on disk.The Distribution of Calcium on the Surface of UMa: An AbundanceDistribution Doppler Image, J. B. Rice and D. E. Holmgren, BrandonUniversityWe present a surface abundance Doppler image of singly-ionizedcalcium for the Bp star UMa based on high signal-to-noise CCDspectra. This map shows striking similarities to that of neutral oxygen(Rice et al. 1997). The Ca ii 866.2 nm line has allowed us to obtain adetailed surface abundance map of calcium for UMa. The calciumabundance map has been used to locate the position of the positivemagnetic pole on UMa at a longitude of 350.8 deg and a latitude of25.8 deg. Calcium is distributed in a ring along the magnetic equator,along which the abundance is [Ca/H] = –5, close to a normal populationI value. This represents an enhancement with respect to other regionsby a factor of ~ 10 3 . A secondary feature is present with [Ca/H]= –6.5.A chemically differentiated stellar wind is proposed as the mainmechanism for generating the surface abundance distribution ofcalcium.An Adaptive Optics Device for Teaching Astronomy, R. M. Robb and E.Steinbring, University of Victoria, and P. A. Delaney, York UniversityThe excitement of high resolution imaging generated by the relativelyexpensive adaptive optics (AO) systems on large telescopes can becommunicated to students. We purchased a tip-tilt AO system fromthe Santa Barbara Instruments Group for use with undergraduate labsat the University of Victoria. It has been mounted on a Celestron 8-inch located on the roof of our building. The ST-8 camera has an“imaging” CCD and mounted beside it is a small “guiding” CCD. Theguiding CCD is read a few times per second and the position of theguide star is found. A calculation is made to find the correctiondisplacement to tip or tilt the right-angle mirror enough to keep theguide star on the same pixels. The light going to the “imaging” CCDreflects from the same tip/tilt mirror so its image is also corrected.While the results are not as dramatic as one might hope, we do measurea small decrease in the FWHM of the images we have obtained. Thestudents learn about feedback in electromechanical systems and thestructure of images.W UMa-type Binary Stars in Globular Clusters, Slavek M. Rucinski,David Dunlap Observatory, University of TorontoA sample of 86 contact binary systems in 14 globular clusters withavailable colour index data in (B-V) or in (V-I) has been analyzed. Alarge fraction of all systems (at least one third) are numerous foregroundGalactic Disk projections over long lines of sight to the clusters. Sincethe selection of the cluster members has been based on the MV (logP, colour) calibrations, the matter of a metallicity-correction requiredparticular attention with the result that such a correction is apparentlynot needed at the present level of accuracy. Analysis of the colourmagnitudeand period-colour relations shows that globular clustermembers have different properties from the Galactic Disk contactsystems. They are under-luminous mainly because of the smaller sizesand, consequently, have shorter orbital periods; the colour-index effectof the diminished blanketing is relatively less important, especially for(V-I). Because of the indications of a bias against discovery of smallamplitudesystems below the Turn Off Point (TOP), efforts at determinationof the frequency of occurrence of the contact systems below the TOPhave been judged to be premature. However, the frequency among theBlue Straggler stars could be moderately well established at about 45± 10 BS stars per one contact BS binary; thus, contact binaries areabout 3 times more common among the BS stars than among the OldDisk population dwarfs. Contact binary systems with periods longerthan 0.6 days are absent in the sample, possibly because the moremassive stars have left the contact binary domain.Radial Velocities of IAU Standard Stars, Colin Scarfe, University ofVictoriaAs part of an ongoing international campaign, over 2000 radial-velocityobservations of IAU standard stars have been obtained with the DAO250JRASC December / décembre 2000

adial-velocity scanner (RVS). In addition, over 100 new velocities fromphotographic plates have been added to those published ten years ago.The standard deviation of the RVS velocities is about three times largerthan that of the photographic data. The RVS velocities were obtainedwith a variety of masks, but zero-point adjustments have been madeempirically between them and between the RVS and the plates. Anabsolute zero-point has been provided by observations of brightasteroids. Comparison between the DAO data and large compilationspublished recently, by groups at the Center for Astrophysics and at theGeneva Observatory, reveals excellent agreement. In particular, apreviously troublesome colour-dependent discrepancy between theGeneva observations and others has been eliminated, by adjustmentsmade recently by the Geneva group, to an extent greater than eventhey had anticipated. The long task of revising the IAU standard systemand providing a list of objects with radial velocities known absolutelyto better than 100 m s –1 , and constant at the same level, now seems tobe nearly complete.Interstellar Clumps: Physical Relations, Magnetism, and Energy, JacquesP. Vallée, National Research Council of Canada’s Herzberg Institute ofAstrophysicsUniversal scaling relations exist in interstellar molecular clouds andclumps, governing the mean physical parameters such as the gas densityn, diameter D, magnetic field B, and gas linewidth W (for recent reviews,see Vallée 1997, Fun. Cos. Phys., 19, 1; Vallée 1998, Fun. Cos. Phys., 19,319). The relations follow the form: ~ D c , ~ k , ~ p ,~ q . In molecular clouds, with D > 1 pc but < 100 pc, theexponents are: c = –1.0; k = +0.5; p = –0.5; and q = +0.5 (e.g., Larson1981, MNRAS, 194, 809). There is a natural separation between cloudsand clumps, occurring near 0.5 pc. One does not expect the physicalbehaviours of clumps (< 0.5 pc) to be the same as for clouds (> 1 pc).In cold clumps, with D > 0.01 pc but < 0.50 pc, the gas density is higherthan in clouds. Clumps are beginning to reveal their secrets, usingobserved findings at high angular resolution. Here I report on a statisticalstudy of the exponent values c, k, p, q for clumps, and on the energycomponents for clumps. The exponent values for clumps are found todiffer from those found by Larson (1981, MNRAS, 194, 809) for molecularclouds. The differences could be indicative of ongoing accretion processesin shocked media. The energy distribution in clumps reveals that thesupport against gravitational collapse in clumps with sizes > 0.1 pccomes mainly from turbulent energy, while clumps with sizes < 0.1 pcare supported by both magnetic and turbulent energies. The clumpsize of 0.1 pc is critical in many other aspects.Pulsation of the Scuti star V369 Scuti, V. A. Volk, E. F. Milone, K. M.Volk and W. J. F. Wilson, University of CalgaryV369 Scuti is a low amplitude, short period Scuti star. These areknown to pulsate in multi-frequency radial and non-radial modes.Photoelectric and CCD differential photometry in BVRI from theRothney Astrophysical Observatory, University of Calgary, and radialvelocity measurements from spectra taken at the Dominion AstrophysicalObservatory, Victoria, were obtained over the summers of 1997 through1999. Fourier analyses of the resulting magnitude, colour and velocitycurves reveal periods consistent with the published principal periodof 0.223 day and its frequency 1 cpd aliases. Multiple frequencies areclearly evident, some of which correspond to p-mode oscillationsexpected by stellar pulsation models. Using Baade-Wesselink precepts,attempts are being made to describe the change in shape and luminosityof the star.Variable Analysis of Compact Sources in the Canadian Galactic PlaneSurvey, S. Wilder, and A. R. Taylor, University of Calgary, and L. A. Higgs,Herzberg Institute of AstrophysicsThe 1420 MHz radio continuum images from Canadian Galactic PlaneSurvey contain tens of thousands of compact radio sources in the planeof the Galaxy down to a flux density limit of about 1 mJy. Some fractionof these sources will be exotic Galactic radio emitters such as energeticbinary star systems, pulsars, and flare stars that can be identified byvariable radio flux. We are carrying out a sensitive search for variableradio sources by combined analysis of the CGPS radio images and theNorthern VLA Sky Survey, which has a similar radio continuum sensitivityand resolution to the CGPS. This variability search is an order ofmagnitude deeper than any previous survey for variable radio sourcesin the Galaxy. We present initial results of an analysis of about 5000sources in an 80 square degree sub-region of the CGPS. The nature ofthe population of radio continuum sources is further investigated bymeasurement of spectral indices by comparison with the WesterborkNorthern Sky Survey images at 327 MHz.Simulations of Planetary Transits of Stars in the Globular Cluster 47Tucanae, M.D. Williams, E.F. Milone, M. McClure, J. Kallrath and C.Stagg, University of CalgaryIn an attempt to answer some of the questions about planets withshort orbital periods, Gilliland et al. conducted an eight-day photometricsearch for planetary transits in the globular cluster 47 Tucanae. Forthe purposes of predicting lightcurves that may be observed, a databaseof lightcurves was constructed. The database spans systems withplanetary radii from half a Jupiter radius up to those of brown dwarfs.Since the problem of modelling the lightcurves of planetary transitsis similar to modelling the lightcurves of eclipsing binary stars, programsthat were originally designed for binary stars were used to model thethese systems. Two programs were used, the Wilson-Devinney (wd98k93)(Milone et al. 2000; Kallrath & Milone 1999) program and as an aid toconstructing an archive, the visualization package Binary Maker 2(Bradstreet 1993). In addition to predicting possible lightcurves, thedatabase will also be used to speed up the modelling of observed systemsby permitting the comparison of lightcurve properties such as thedepth and the width of observed transits with those already modeledto estimate the system parameters. The parameters of the planetarysystem can then be refined using the Wilson-Devinney code and themethod of differential corrections. The first observation of a planetarytransit was made for the star HD209458. Photometric data fromCharbonneau et al., and Henry et al., were used to determine theparameters, like planetary mass and radius, of the HD209458 system.This work was supported by grants to EFM from the U of C ResearchGrants Committee and NSERC.December / décembre 2000 JRASC251

Education NotesRubriques pédagogiquesIMPROVING THE TEACHING OFASTRONOMY 101 THROUGH TUTORIALSby Wayne A. BarkhouseHalifax Centre, RASCElectronic Mail: barkhous@astro.utoronto.caand Chris R. BurnsUniversity of TorontoElectronic Mail: burns@astro.utoronto.caAbstract. While lectures are a vital component to teaching an undergraduate course in astronomy, there are certain topics which aremore efficiently handled in a tutorial setting. In this paper, we discuss the role tutorials can play in helping students understand some ofthe basic concepts in astronomy by presenting specific examples from a first-year astronomy course offered at the University of Toronto.Five activities are described, two of which are excellent examples of the hands-on approach to teaching and learning, and are also suitableto the study of astronomy at the middle or senior high school level.Résumé. Bien que les cours sont d’une importance vitale dans l’enseignement de l’astronomie au niveau premier cycle universitaire, lesclasses dirigées sont plus pratiques pour permettre d’aborder des sujets particuliers. Dans ce rapport, nous discutons du rôle des classesdirigées pour aider les étudiants à comprendre certains principes de base en astronomie, en présentant des exemples particuliers puisésdans le cours de premier cycle offert à l’université de Toronto. Nous décrivons cinq activités, dont deux sont d’excellents exemples de laméthode ‘sur le tas’ d’enseigner et d’apprendre. Ces activités s’appliquent aussi à l’enseignement de l’astronomie au niveau secondaire.SEM1. IntroductionThe traditional method of teaching first-year astronomy studentshas relied upon the use of the so-called “lecture” mode to conveyinformation. Despite its convenient format for instructing largenumbers of students, the “lecture” mode has several disadvantages,including the lack of direct interaction with each student and theinability to teach certain concepts which require different visualizationtechniques. These disadvantages can be addressed through the useof tutorials.For the past several years, the Scarborough College at theUniversity of Toronto has made extensive use of tutorials for teachingfirst-year astronomy students. The tutorials are conducted by graduatestudents and typically contain 15–30 students. The tutorials canprovide a casual environment in which students feel comfortablecontributing to the class.In this article we present several examples of concepts whichare more effectively taught in a tutorial-like atmosphere rather thanthe traditional lecture-style mode.2. Activities and DemonstrationsIn this section, we present several examples of activities we haveperformed in tutorials at Scarborough College. We describe eachactivity, explain its motivation, and list its advantages and disadvantages.2.1 The SeasonsA common problem with teaching astronomy is that students beginthe course with preconceived notions about how the universe works.A good example is the reason why we have different seasons. Intextbooks, students are introduced to the notion that the Earthrevolves around the Sun in an ellipse. Unfortunately, most textbooksexaggerate the ellipticity, and the students can be left with theimpression that the Earth is much closer to the Sun for part of theyear. If students formerly thought that the Earth experiences seasonsbecause of its changing distance to the sun, the ellipticity of the Earth’sorbit will no doubt reinforce this notion.In this activity we try to get the students to re-evaluate thisconcept individually through an active discussion, or debate. Webegin by asking the students to propose any hypotheses to explainwhy there are seasons. Hopefully, the right answer will be suggested,but if not, the tutorial leader can propose it. The goal is not necessarilyto get to the correct answer, but rather to show how one can falsifydifferent hypotheses.Once we have several suggestions, a vote is conducted on whichone is the correct answer, eliminating all but the two (or more) mostpopular choices. We then split the students into teams and have themjustify their choice. Finally, the tutorial leader initiates a discussionbetween the teams, where each team attempts to falsify the other’sposition.252Journal of the Royal Astronomical Society of Canada, 94: 252—254, 2000 DecemberDecember / décembre 2000

Advantages:• Students learn about how to apply deductive reasoning• Students (hopefully) arrive at the correct conclusion on their own• It is a good way to “break the ice”Disadvantages:• Can take a long time• Can be frustrating to implement with unresponsive students2.2 Constellations and the ZodiacWe have found that some students can examine a good diagram froma textbook and immediately understand what is being depicted. Otherstudents have more trouble imagining what the two dimensionaldrawing is explaining about the three dimensional universe. In thefollowing activity, we attempt to explain the Sun’s apparent yearlymotion through the constellations of the Zodiac by making thestudents a part of the demonstration.We start by rearranging the classroom chairs to form a circle,with one chair placed at the centre where the tutorial leader sits.Pictures of the constellations are attached to the walls of the room,including the floor and ceiling, with the Zodiac constellations placedat eye-level.The students are told that the tutorial leader is the Sun, whileeach person seated represents the Earth at some point in its orbit.To make the point even clearer, the tutorial leader can hold a largeyellow ball, while the students pass around a smaller blue ball.The tutorial leader then asks the students to pass the Eartharound the circle and as each student gets the ball, they tell everyonewhich constellation the Sun appears to be in. If the constellations arein the correct order, then one can assign dates to each position alongthe Earth’s orbit. By having the students turn around to face the wall(and hence away from the “Sun”), they can see which constellationsare visible during the evening.Advantages:• Students get to think in three dimensions• Students get to participate• Students see the value of a model in understanding difficultconceptsDisadvantages:• Difficult to do with large numbers of students (> 30)2.3 Stellar ParallaxThe setup is identical to the previous one except now a “foregroundstar” is placed between the circle of chairs and the wall of constellations(the “background stars”). The students should now be comfortablewith the Earth going around the circle of chairs with the Sun in themiddle. However, now their attention will be focussed on the star.Each student in the circle tells the tutorial leader where theforeground star appears to be with respect to the background stars.The tutorial leader notes these positions and the students will be ableto ascertain the periodic movement of the apparent position of theforeground star. The students can also attempt to measure theparallactic angle and use trigonometry to calculate the distance tothe star.The advantages and disadvantages are similar to that experiencedfor the “Constellations of the Zodiac” tutorial.2.4 Sidereal vs. Solar TimeWe have found that this concept is one of the most difficult ones toteach in astronomy. Even the best diagrams lack motion and thereforethe notion of “time.” Scarborough College is equipped with a smallplanetarium (which can fit about 15 people), which we find is anexcellent resource for demonstrating difficult concepts, includingsidereal time. We also use celestial spheres (clear plastic spheres onwhich the constellations are inscribed and which have the earth atthe center of the sphere) to demonstrate the same things. In this way,the students can see what is happening from two different perspectives.We begin with the usual introduction to the night sky, includingthe constellations of the Zodiac. We then define, and demonstrate,a solar day and a sidereal day. Our planetarium is equipped with alarge “Sun” and a meridian, so it is very simple to demonstrate a solarday: the time between meridian crossings of the Sun. We thendemonstrate the sidereal day as the time between meridian crossingsof the stars. The students are then asked whether these times are thesame. The students are quick to realize that during the time betweensuccessive meridian crossings, the sun has moved a little along theecliptic, whereas the stars are still in the same location. The wholeexercise is repeated using the celestial spheres (which also have ameridian and moveable Sun).Advantages:• Students see phenomena in “real time”• Requires student participation to work well• Good practice for the teaching assistant’s “showmanship”Disadvantages:• For some students, seeing things from both perspectives can bemore confusing than enlightening• Requires technical expertise2.5 Telescope SimulationWith class sizes of about 150, it is not practical to have students visitan observatory and actually use a telescope to collect data. Fortunately,with the advent of networked computers, a lot can be done in acomputer lab to simulate how a real telescope works. Students canalso acquire real data from the Internet, which they can use to doprojects like main-sequence fitting of clusters. For many students,this type of activity gives them the feeling of doing “real” astronomyand an appreciation of the many uncertainties involved in acquiringdata through instruments.Until recently, we used the “TS24” telescope simulator to havestudents perform main sequence fitting of an open cluster. Thesimulator was very sophisticated, and one could easily incorporateDecember / décembre 2000 253JRASC

eal data into the program, including interstellar extinction and propermotion. The students were presented with different telescopes (finder,main mirror) and several instruments (eyepieces, photometers, CCD’s).The objective was to find a cluster, centre the telescope, and takeexposures with U, V, and B filters. The students then calculated thecolour indices, classified the stars, plotted an HR diagram, and didthe main-sequence fitting.Unfortunately, TS24 is no longer maintained and does not workwell with the Windows operating system. Therefore, we were forcedto abandon it (the Scarborough computer centre only maintainsWindows NT computers). However, other telescope simulator programsare available, one of which is “Project CLEA.” This program is free andcontains astronomy laboratories which are written for the Windowsand Macintosh operating systems. We have not had a chance to usethese in a tutorial setting, but one of their labs, entitled “PhotoelectricPhotometry of the Pleiades,” will be implemented in the coming year.Advantages:• Incorporates many concepts into a single activity (experimentaluncertainty, signal-to-noise ratio)• The activity is very “hands-on,” which many students preferDisadvantages:• Requires substantial setup and testing of softwareIn order to gauge how successful tutorials are in helping to teach firstyearastronomy students, it should be noted that for the past fiveyears, students who regularly attend weekly tutorial sessions have,on average, a 20% higher grade compared to those students who donot attend tutorials. Students in general prefer the tutorial-style modeof teaching, and this preference is reflected in the higher gradesachieved.3. ConclusionFor the past several years, an extensive program of using tutorials toteach first-year astronomy students has been in place at ScarboroughCollege, University of Toronto. These tutorials are implemented bygraduate astronomy students who generally teach approximately 15to 30 students per session. In each case, the tutorial activity offersthe students a learning opportunity they may not get in a largeclassroom environment. In the case of the seasons debate, they seefirst-hand the thought processes involved in hypothesizing andverifying a theory. For the zodiacal constellations and parallax activities,they get to interact with the model instead of just looking at it. Withthe planetarium and celestial sphere exercises, they can “play withthe knobs” and experiment with the night sky. Lastly, the virtualtelescope lets them appreciate what goes into the scientific resultswe present most often as a fait accompli. We therefore believe thatthe most effective method for teaching these students is to use tutorialsto complement the lecture-style mode of teaching.Wayne A. BarkhouseDepartment of AstronomyUniversity of TorontoToronto, Ontario, M5S 3H8CanadaChris R. BurnsDepartment of AstronomyUniversity of TorontoToronto, Ontario, M5S 3H8CanadaWAYNE A. BARKHOUSE is a Ph.D student in the Department of Astronomy at the University of Toronto. He received his BSc. in Physicsand MSc. in Astronomy at Saint Mary’s University. He is an attached member of the Halifax Centre, RASC, and is the Editor-in-Chief ofthe Journal of the Royal Astronomical Society of Canada.CHRIS R. BURNS received his BSc. in Physics from Bishop’s University, then his MSc. in Physics from the University of Toronto. He is currentlyworking on a Ph.D in Astronomy in the Department of Astronomy at the University of Toronto.254JRASC December / décembre 2000

Across the RASCdu nouveau dans les CentresSociety News/Nouvelles de la sociétéSubmitted by Kim Hay, National Secretary (kimhay@kingston.net)It’s hard to believe that Christmas isjust around the corner. I would liketo wish all members of the RoyalAstronomical Society of Canada a VeryMerry Christmas and a Happy New Year(New Millennium or not… that is still thedebated question). May all your Christmaswishes come true, and may you get thatnew Nagler eyepiece you have beendreaming of. Remember, there are greatastronomical gifts available from theNational Office, such as the 2001 Observer’sCalendar, The Observer’s Handbook, TheBeginner’s Observing Guide, or perhapsa membership for a friend. Please visitthe RASC website at www.rasc.ca andlook under RASC Promotions.On September 23 rd , 2000, the BellevilleAstronomy Club (www.magma.ca/~glisk)and the Kingston Centre, RASC(www.rasc.ca/kingston) had anastronomical get-together at Presqu’ileProvincial Park. Though the weather didnot co-operate, it was an excellent firstattempt at a local star party. There were27 in attendance, with talks from bothclubs at night. Topics of the talks includedhomemade tripods for binoculars andtelescopes (Les Dempsey, www.blvl.igs.net/~ldempsey), youth group observing(Hank Bartlett – Kingston), amateurtelescope making (Kendra Angle –Kingston, Dave Pianosi –Belleville/Kingston, Greg Lisk – Belleville),and a solar system made to scale out ofwood for demonstration purposes fromJoe Sheilds (Belleville).Some members elected to stay upand wait out the clouds by watchingmovies, roasting marshmallows, orwatching and chasing the racoons thattended to visit the campsite. Around 3:30a.m., the clouds did part somewhat, withthe appearance of Orion, Jupiter, Saturn,the Pleiades, and Taurus. This, however,was short-lived and the clouds rolled inagain. By daybreak the clouds started toclear, with the sun shining in the earlyafternoon.On his own accord, a local Kingstonmember has purchased a Star Lab PortablePlanetarium to bring education andentertainment to the public. TheodoreMicholias operates it, all for the love ofastronomy, under the name of GeminiSpace Exploration. So far, Theodore hasshown his planetarium to two publicschools and has set it up at the localChapters bookstore. His program is madeup of presentations on the Canadian SpaceAgency, Greek mythology, and theconstellations. If you are interested inthe Star Lab Portable Planetarium, pleasecontact Theodore at geminispace@home.com.RASC Award forThis year’s junior RASC award for excellencein astronomy was awarded to Jonathan Sickfor his project Predicting Solar Activity.Excellence in AstronomyThis year, the RASC award for excellencein astronomy was presented at the Canada-Wide Science Fair held in London, Ontariofrom May 14 to 20, 2000. The award isgiven to junior and intermediate/seniorstudents who are judged to have anoutstanding project related to astronomyin the area of observations, instrumentconstruction, or other related areas. Thisyear’s junior prize winner is JonathanSick, Queen Elizabeth Jr. & Sr. High, Calgary,AB. Jonathan won a cash prize of $200for his project entitled Predicting SolarActivity. The intermediate/senior awardThis year’s senior RASC award for excellencein astronomy was awarded to Heather Hughsonfor her project Vacuum Primordium.was presented to Heather Hughson fromWaterloo Collegiate Institute, Waterloo,ON. Heather won a $300 prize for herproject entitled Vacuum Primordium.Congratulations!Congratulations to...At the National Council meeting held inDecember / décembre 2000 JRASC255

Toronto on October 14 th , 2000, severalmembers of the RASC received theirMessier & NGC Certificates. Recipientsof the Messier Certificates were ArnoldL. Rivera (Edmonton), Paul Ellard(Okanagan), Lawrence J. Burgess (Windsor),and David Marchand (Windsor). Recipientsof the NGC Certificates were Arnold L.Rivera (Edmonton), Guy Mackie(Okanagan), and Ron Scherer (Okanagan).Congratulations to everyone on completingthe requirements for the certificates, andmay your next venture take you to thenext level.Paul Boltwood (Ottawa Centre), ofStittsville, Ontario has been honouredwith an asteroid named after him. Thisis the citation, forwarded from Brian G.Marsden of the IAU Minor Planet Centre:(8785) Boltwood — A series of stacked imagestaken on October 25 th , 2000 with a totalexposure of 76 minutes (image by Paul Boltwoodwith his 16-inch Newtonian telescope andhomebuilt CCD camera).From MPC 41384 on Oct. 13: (8785)Boltwood = 1978 RR1, discovered 1978Sept. 5 by N. S. Chernykh at the CrimeanAstrophysical Observatory. Paul Boltwood(b. 1943) is a Canadian specialist incomputer systems and outstanding amateurastronomer. He monitored the peculiarobject OJ 287 for some two years. He alsoobtained deep-sky CCD images with limitingmagnitude 24.5 using a home-built 0.4-m reflector. Congratulations, Paul, for agreat personal accomplishment and forall of us in Astronomy.David Levy, at the fall meeting of theAmerican Association of Variable StarObservers (AAVSO), was awarded theWilliam Tyler Olcott Award. This newaward of the AAVSO is intended to honourindividuals who have had an impact inincreasing the public awareness ofastronomy and variable stars.Astronomical Society of the Pacific Awards 1Two Canadian astronomers, one professional (PeterStetson, Victoria Centre) and one amateur (PaulBoltwood, Ottawa Centre), receive awards from theAstronomical Society of the Pacific.Maria and Eric Muhlmann AwardPeter B. Stetson of the Dominion AstrophysicalObservatory is this year’s recipient of theMaria and Eric Muhlmann Award, givenannually for recent, significant observationalresults made possible by innovative advancesin astronomical instrumentation, software,or observational infrastructure. He is theauthor of one of the most widely used (andpraised) data-reduction packages inastronomy — his DAOPHOT was firstdescribed in the astronomical literature in1987. The program, which can preciselydetermine the brightness of point sourcesimaged with area detectors, was specificallydesigned for measuring stars in very crowdedglobular cluster fields. DAOPHOT allowsfor the two-dimensional characterizationof the brightness distribution of a pointsourceand then applies this “point-spreadfunction”to all objects in a CCD image.Overlapping stellar profiles can be accuratelydeconvolved by fitting the point-spreadfunctionsimultaneously to many objectsin an image. The development of DAOPHOTwas as significant to the advances in thestudy of globular clusters as was the availablityof CCDs. DAOPHOT has been steadilyimproved in the decade since its introductionwith its latest incarnation named ALLFRAME.Stetson has put his code to good use andhas been one of the leaders in the broadfield of globular cluster studies. He has alsoplayed a major role in the steady refinementof our knowledge of the absolute age of theGalaxy and the distribution of ages in thehalo of the Galaxy — this latter work is keyto understanding the early epoch in theformation of the Galaxy.Steven VogtAmateur Achievement AwardPaul Boltwood has been an amateurastronomer for forty years. He is this year’srecipient of the Society’s AmateurAchievement Award in recognition of hisindividual accomplishments in thedevelopment of hardware and software forprecise deep-sky imaging, his research onbrightness variations in active galactic nuclei,and his studies of near-nucleus activity inComet Hyakutake. In May 1998 Boltwood1Reprinted with permission from Mercury and the Astronomical Society of the Pacific.obtained the deepest image ever obtainedwith amateur equipment — a V magnitudeof 24.1 collected over a twenty-hour period.Prior to the invention of CCD imaging, eventhe 200-inch Palomar telescope could onlyachieve a limiting magnitude of 23. Boltwood,however, used a 40-cm, homebuilt telescopeand CCD camera located in his backyardobservatory in suburban Ottawa, Ontario,Canada. What is notable about hisaccomplishments is the care and attentionto detail he applies to his research. He strivesfor the best possible standard of care andachieves professional-quality results. Hisnomination included letters ofrecommendation from astronomers at YaleUniversity, the University of Colorado, theUniversity of Toronto, and the RoyalAstronomical Society of Canada. He haspublished numerous scientific papers andhas collaborated with researchers at a numberof institutions throughout the world. Theaward committee was particularly impressedwith the breadth and sustained nature ofPaul Boltwood’s contribution to astronomy.He is a model of how amateurs can makeunique and valuable contributions to science.Wayne Rosing256JRASC December / décembre 2000

A Candle in the Darkby Bill Broderick, Kingston Centre (broderic@kos.net)Illustration by Brian G SegalMy “Candle in the Dark” projectbegan a few months ago whenI conceived the idea of writingan astronomy column for an astrologypublication. As it happens, I have a friendwho publishes an astrology newsletter,and she is also interested, somewhat, inastronomy. She has actually taken a popularastronomy course and so knows moreabout astronomy than most astrologersI have met. She is particularly fascinatedby eclipses (as they pertain to astrology)and has become something of an experton them, particularly on the Saros cycle,the 18-year period after which solar andlunar eclipses tend to repeat themselvesunder nearly the same conditions.She had already published severalitems I had written, so the idea of a regularcolumn appealed to her. I dashed off threeone-page essays for the upcoming fallmonths, and we were in business. Overthe summer, with all kinds of other thingsgoing on, ideas still came fast and furious,and before the season was over I hadenough essays to go for a couple of years(if it lasts that long).Why an astronomy column in anastrology newsletter? Well, astrologers(at least the ones I have known) tend tobe fairly smart people. They are notuneducated. Some ofthem even run reasonablysuccessful businesses orfollow professionalcareers in various fields.In other words, a lot ofthem are not dummies.(Considering the sheeramount of informationand work that used togo into setting up astandard horoscopebefore the age ofcomputers, astrologershad to be smart then,and I think most are stillsmart now.) They justhappen to believe fervently in astrology.By extension, they have an interest inastronomy, although they usually do notknow that much about it. Astrologers areyour classic “seekers of truth.” They believethey have found it in astrology.What exactly do astrologers believe?Tenets of AstrologyCarl Sagan, one of the most brilliantscientific popularizers of science andastronomy of our time, once made referenceto the “tenets of astrology.” I have neverbeen able to find them anywhere, but Ionce studied astrology, so I wrote up myown. My astrology friend agrees withthem, so here they are:1. Life and events on Earth and in ourlives are influenced by forces and eventsin the cosmos.2. The Sun and planets, individually andin combination, are the major sourcesof cosmic influence.3. The influence of each planet is differentbut is altered or coloured:a) by its position on the zodiac (thatis, the ecliptic, the apparent pathof the Sun in the sky),b) by its position in the houses (the12 divisions of the sky whichsupposedly rule various aspectsof our lives. These begin at theeastern horizon, continue aroundunder our feet to the westernhorizon, and continue over ourheads and back to the easternhorizon), andc) by the angles (or aspects) it makesrelative to other planets (trines,squares, sextiles, conjunctions,oppositions, etc.).4. Certain points, such as the rising pointand mid-heaven, lend particular strengthor emphasis to a planet which happensto be situated there at the moment ofbirth.5. The 12 signs, Aries, Taurus, Gemini,etc., begin at the point of the vernal(spring) equinox, where the Sun (onthe ecliptic) crosses the celestial equatoron or about March 21 each year.Traditionally, this is the First Point ofAries.6. The 12 houses begin at the point onthe ecliptic that was on the easternhorizon at the moment of birth.7. Signs are labeled “Air”, “Earth”, “Fire”and “Water”, and are further labeled“Cardinal”, “Fixed” and “Mutable.”These terms are derived from supposedqualities of the signs, which modify orcolour the influence of the planets.“Very often we even resentthe implication that it is abelief. We do not believe, weknow. Certainly, astrologersare convinced that theirs isnot just a belief but ancientknowledge. They also thinkthat they have personallyverified it and that, therefore,they know, they do notbelieve.”December / décembre 2000 JRASC257

Beliefs are FixedOne of the things I have learned over theyears is that you cannot change the beliefsor opinions of people by arguing withthem. Rightly or wrongly, an attack onone’s belief or opinion is perceived as anattack on the person and is rebuffed.Whether it is religion, politics, naturalhealing, chiropractic, homeopathy, astrology,I Ching, or any other brand of belief, ifwe have made it our own, we resent anyattempt on the part of someone else tomake us change it.Very often we even resent theimplication that it is a belief. We do notbelieve, we know. Certainly, astrologersare convinced that theirs is not just abelief but ancient knowledge. They alsothink that they have personally verifiedit and that, therefore, they know, they donot believe. For that reason, I am verycareful not to say anything critical aboutastrology. Even if my editor allowed meto do so, I would very quickly lose credibilitywith the readers.My FocusThe focus of my articles, then, is simplyto write about astronomy and things thatrelate to it, such as my own fascinationwith the subject. These include my firsteclipse trip, what can be seen in the sky,how to find things in the sky, how to buya telescope (buy binoculars first), howthe planets move (in ellipses), currentevents (water on Mars, possible life onMars), the nature of the “face” on Mars(it is a hill), the scientific method, someof the controversies that have arisen(expanding universe versus steady state),UFOs, extraterrestrial life, interstellartravel, etc. The idea is not to challengethe astrological world view but to awakenan interest or curiosity in astronomy andscience.I try to make my titles provocative.Here are a few examples:• The Thief Who Stole the Night: an essayabout urban light pollution and itssolutions;• A Pinch of Stardust: how heavy elements(everything heavier than hydrogen)were created in the stars and stellarexplosions and how, therefore, we areall pinches of stardust;• Air, Earth, Fire, Water: how these“traditional” elements have shapedour planet;• Johannes Kepler and His WonderfulEllipse: about planetary motions,of course;• Ice and Snow in Space: comets andsuch; and• Oh Be a Fine Girl, Kiss Me!: theclassification of stars based on theHertzsprung-Russell temperatureluminositydiagram. The title is amnemonic used by astronomy studentsto remember the order of stellarclassification beginning with the hottest:O, B, A, F, G, K, M.Stars for SaleAn article published just before Christmaswas “Stars for Sale.” The essay concernedstar-naming companies, such as theInternational Star Registry. For $35 or$50 or whatever, these companies willname a star after you, your loved one,your kid, maybe even your dog. You geta nice fancy certificate attesting thathenceforth, star such-and-such will beknown by the name you have requested.You also get a chart which is supposedto help you locate “your” star, but of courseit is much too dim to be located with thenaked eye. If you take your chart to anastronomer and ask to see it in a telescope,chances are you will be told that the chartis too imprecise to possibly be of any help,that if we do find the right field there willlikely be several stars in it, and anyway,none of them is “your” star because onlythe International Astronomical Union(IAU), an organization of professionalastronomers, has the authority to namestars. People are generally shocked tolearn that their certificate has no officialvalidity whatsoever, that it is only a noveltyitem not worth the paper it is printed on,that they have in fact fallen for a rathersilly scam that happens to be, if not illegal,at least not very ethical. Maybe the articlewill help put a dent in the sales of starnamingcompanies. That would be nice.ConclusionWe live in a pretty dark world, full of“That is what my ‘Candle in theDark’ project is all about; sheddinga little light, revealing a little truth,helping people to see a few thingsmore clearly.”misconception, ignorance, false belief,fear, and superstition. The “forces ofdarkness” want it to remain that way, andthey seem to get their way far too often.Belief in astrology, as the 1997 YorkUniversity Second Survey of the Attitudesof University Students to Astrology andAstronomy by Michael De Robertis andPaul Delaney showed (see the June 2000issue of the Journal), is widespread evenamong the fairly scientifically literate.Will a few essays about astronomy in anastrology publication make any difference?I do not know. I do know that in order tosee, we must have light. In the modernworld, science is the brightest light wehave. Carl Sagan’s book The Demon-Haunted World: Science as a Candle inthe Dark reminds us that by letting thislight shine wherever we can, we may helpthose who are having trouble seeing.That is what my “Candle in theDark” project is all about; shedding alittle light, revealing a little truth, helpingsomeone to see a few things more clearly.It is possible I will get a few readersseeing and thinking, and when you getpeople really thinking, as opposed toonly thinking they are thinking, wonderfulthings can happen.Bill Broderick is a member of the KingstonCentre and served as editor of the centre’snewsletter Regulus for several years. Hechaired the National Light Pollution AbatementCommittee from 1995 to 1998, and continuesas a member of the committee. He is involvedwith various public issues, among themsmoking and light pollution. A member ofthe Ontario Skeptics, he rides herd on astrologyand other voodoo-sciences from his lair nearBelleville, Ontario.258JRASC December/ décembre 2000

At the EyepieceRoyal Reflectionsby Guy Mackie, Okanagan Centre (guy.m@home.com)As patriarch of the northern skies,the constellation Cepheus wearsits reflection nebulae with asubtlety reminiscent of the “EmperorWho Wore No Clothes.” When I decidedto observe all the diffuse nebulae inCepheus that are listed in Burnham’sCelestial Handbook, I was unaware of theambitious nature of the observing challengeI had set for myself. Vast sweeps of faintcloud and small but bright nebulae withtantalizing hints of structure combinedto make an excellent exercise for developingobserving skills. Stellar ejection nebulaecontain elements of both emitted andreflected light, and I was pleased to find(for the sake of this article’s title) that allof the nebulae in Cepheus listed byBurnham’s contained enough reflectedlight to be visible without using any lightfilters.The first target for my 12.5-inchDobsonian telescope is situated on thefront step of the house-shaped Cepheus.Just a few steps southwest of theconspicuous yard-light “Garnet Star” MuCephei is a cluster and an extremely largediffuse nebula with the combineddesignation of IC 1396. Using a low powerof 63×, the centre of the cluster is markedby the close triple system of Struve 2816,containing a bright yellow star with twodimmer white/blue companions. Thisdistinctive triple sparkles, along withseveral dozen other members of themoderately rich cluster IC 1396, to nearlyfill the entire low power field against adark background encircled by a faintfringe of nebulosity. A slight nudge of thescope off of the cluster in any directionwill reveal a faint murky cloud that, likethe Rosette Nebula, is detected more bythe reduced stellar population than bythe presence of nebulosity. This very dimA 10-degree high finder chart for NGC 7782 showing stars to about 8.5 magnitude(ECU Chart by Dave Lane).nebula requires a dark transparent skyand well-developed dark adaptation beforethe eye can be tuned to truly appreciatethis elusive shade of pale. I found that aUHC filter did offer a slight enhancement;however, while exploring the full extentof this sprawling nebula, I came to preferthe unfiltered view as it allowed the fullcontrast with the rich star fields in thisarea, which brushes the nearby MilkyWay.On a night of excellent seeing, whensweeping the area southwest of BetaCephei with medium/low power, I usedaverted vision to notice NGC 7023 as asmall, moderately bright cloud surroundinga light, straw-coloured 7 th magnitude star.It soon became apparent that the starand its associated cloud were themselvesset within a large faint circular haze.Increasing the magnification to 158×reveals structure in the cloud similar toa very faint Orion nebula as the centralstar is muted by a glowing arc, extendingin a north to south direction, with longtendrils sweeping off the ends. An extendedobservation period using averted visionenhances the bright region north of thecentral star and reveals dark lanes andbays. The entire 0.4-degree field is stronglyaffected by the dim haze of theencompassing nebula, which a move tothe surrounding rich dark star field revealsto best advantage.Using the 1/2 degree distance betweenM52 and NGC 7635 (the Bubble Nebula)as a guide, travel just less than 1 degreeslightly north-of-west from NGC 7635,December/ décembre 2000 JRASC259

and the faint glow of NGC 7538 will enterthe view. If you use a low power to yield63×, NGC 7538 is a dull gray oval glowaround two faint stars. At 88×magnification, the oval, extending fromnorthwest to southeast, fans out and isslightly brighter at the northwest end.NGC 7538 “brightens” moderately withthe use of a UHC filter, but even at higherpower, none of the filamentary structurementioned in Burnham’s was revealed tome.As a member of the Finest NGC list,NGC 7129 was a familiar visual object forme, and I was delighted that it was alsoincluded in a talk given by Dr. Chris Purtonat a monthly centre meeting. In his studiesof Dissociating Stars, Dr. Purton has thusfar only found 3 such stars in our galaxy,and one of them makes its home in NGC7129. Dissociating Stars are believed tobe newly formed stars that can be identifiedby the presence of their surroundingatomic hydrogen nebulae, which can bedetected in radio signals at a 21-cmwavelength. The 10 th magnitude type Bstar (BD65+6138) is surrounded by anatomic nebula of over 3.5 light-years inextent, much larger than the visual sizeof NGC 7129. Dr. Purton estimates thatthis dissociating star is only 1000 to 1800years old, a mere infant by cosmologicalstandards! At my low power of 63×, NGC7129 is seen as a moderate glow arounda small triangle of stars. At 158× a brightknot of nebulosity appears star-like onthe north edge of the triangle, to make asquashed diamond shape. It may be thatthe two easterly stars of the triangle areactually nebulosity, but they appear stellarin my scope. Amazingly there are fourother reflection nebulae easily containedwithin this narrow (0.4°) field. I was ableto pick out the faint combined glow ofIC 5133 and IC 5132, appearing as a meagermist around an L-shaped asterism justnorth of NGC 7129. Using averted visionwith some tube movement I was just ableto detect the subtle glow of IC 5134 arounda star near the edge of the field to thenortheast.It is little wonder, with this plethoraof mirrored majesty, that confusion reignedin the royal house of reflections when Iwent in search of NGC 7133, the fourthcompanion to NGC 7129. Unlike the ICobjects, the reclusive NGC 7133 is listedby Burnham’s, but it is so much a part ofNGC 7129 that I kept overlooking it. Afterfailing to positively locate NGC 7133 anumber of times, I examined a DigitalSky Survey image of the area, wherein thefaint cloud of NGC 7133 is shown snuggledup to the south-east edge of NGC 7129.Using a 10-mm Radian eyepiece (158×)for a lengthy observation of over an hourI was able to detect NGC 7133 for just afew brief periods when the diffuse glowwould burst into averted visionmomentarily. I am not confident of thisobservation as it may well be that, likethe Emperor, I was fueled by suggestionprovided by the photograph and saw onlywhat I hoped to see.Presenting a real challenge to thisobserver, NGC 7822 well deserves its firstplace position on the RASC ChallengeObjects list. Using open cluster NGC 7762and its 5 th magnitude companion star asa convenient pointer, I had to sweep 5 or6 times to the northeast before the subtleglow of NGC 7822 registered on myconsciousness. This near 2-degree gullwingedarc of faint nebulosity is bestappreciated by drifting beyond the cloudto the bordering inky blackness. Aftergrowing familiar with the contours I couldfollow the northern edge with some ease.On a night of excellent seeing at the MountKobau Star Party I noticed dark lanessweeping from west to east within thisdusty denizen of the king’s realm.After completing the project witha 12.5-inch mirror I re-observed with my8-inch Celestron Starhopper Dobsonian.Of the six reflection nebulae listed byBurnham’s only NGC 7133 refused to yieldto the 8-inch aperture. The guidepostsof Struve 2816 and a subdued NGC 7762remain relevant, and reacting very wellto the use of averted vision, NGC 7023showed its N-S extension. A first-timepositive observation of NGC 7822 withan 8-inch mirror may have been more ofa challenge than I could have met, butlike shadow ripples on a pond, the subtlewaves of reflection were there.My experience exploring the reflectivecloak of Cepheus has been an enjoyablechallenge, and I encourage others to accepthis royal patronage.Guy Mackie enjoys observing from the clearand dark hillsides near Kelowna, BritishColumbia. He recently completed the RASCMessier list, and over half of the Finest NGCObjects with his 8-inch Dobsonian. He enjoysskiing, hiking, and camping with his family.260JRASCDecember / décembre 2000

Orbital OdditiesConjunction Junctionby Bruce McCurdy (bmccurdy@freenet.edmonton.ab.ca)Ihave long been captivated by the musicof the spheres. The interplay amongthe orbits of the planets, their satellites,and debris of the solar system, results inan enormous variety of harmonics,resonances, and variations on a theme.The cyclical interactions among afascinating cast of characters can rangefrom the subtle but steady rhythmicbuildup of an occultation series to thecymbal crash of a total eclipse.In this first article of what I hopebecomes a series, let’s look at interactionsbetween Earth and Venus, which arelargely played out in the “simple” timesignature of 13:8.I made my first acquaintance withthe planets in the winter of 1985. A friendpointed out a fine conjunction betweenMars and Venus, which I had neverpreviously identified despite havingachieved the ripe old age of twentysomething.I expected the more famous(at least in science fiction circles) Marsto be the more impressive object, but itwas a relatively faint red dot about 1% asbright as its companion. It was Venustherefore that left the lasting impressionof a neighbouring world; in fact, despiteMars’ reputation, in many ways Venus isthe more Earth-like planet in diameterand mass, not to mention its acid rainand greenhouse effect. Its large, steady,and brilliant spot of pure white is a sightthat to this day has never failed to bringme pleasure.As Sky & Telescope’s E. C. Krupp oncewrote in an attention-grabbing openingsentence, Venus was “named by theRomans for the voluptuous goddess oferotic love.” To the telescopic observer,The relationship between transits and occultations of Venus is depicted in this pair of diagrams.Whereas transits occur in pairs (as shown upcoming in 2004 and 2012) or even single events,occultation series last much longer due to perspective effects. In the first case Venus’ heliocentriclatitude (distance from the ecliptic) is greatly exaggerated by its close proximity to Earth; in theother it appears compressed due to the planet’s position beyond the Sun at superior conjunction.The chords of the successive occultations are therefore roughly six times closer together thanthose of the transits. In the transits shown, Venus moves east to west (left to right) relative tothe Sun near its descending node, and in the opposite direction near the ascending node duringthe occultations. Note that the chords are not precisely parallel due to the gradual eastwarddisplacement of the node from one event to the next (diagrams courtesy of Russell D. Sampsonand the author).however, Venus is downright demure,never shedding her atmospheric veil forany man, no matter what size hisinstrument! Surface details which arebrazenly strutted by the Moon and moregrudgingly revealed by Mars are foreverhidden on Venus by a bland yet crushinglydense, poisonous atmosphere. Theearthbound observer must therefore becontent watching dramatic changes inour sister planet’s size and shape as herdistance from us varies by a factor of sixduring each cycle.This past June Venus reached thefar side of its orbit as seen from Earth,its so-called superior conjunction. Butthis wasn’t any old superior conjunction;in 2000 June Venus was in fact occultedby the Sun, an unobservable but notuninteresting event that occurs on averageless than once per decade. This occultationapproximates the reverse of a still-rarerphenomenon: a transit of Venus acrossthe face of the Sun. One of the most eagerlyDecember/ décembre 2000 JRASC261

anticipated events in astronomy will occuron 2004 June 8, namely the first transitof Venus since 1882. Think about that fora second: nobody alive today has observeda transit of Venus. What can we learnabout transits from this year’s happenings?“Superior” conjunctions of Venus arespectacularly misnamed. At its furthestpossible distance from Earth, the tiny (10arc second) full disc of the planet crawlsever so slowly nearer the Sun for severalmonths and takes equally long to finallyput enough apparent distance betweenitself and our brilliant star to make itsnext appearance in the evening sky. Bycontrast, at so-called “inferior” conjunction,Venus swoops between the Earth andSun at breakneck speed, its huge (60+arc second) but skinny crescent rapidlychanging in appearance as it catapultsfrom evening to morning sky virtuallyovernight.The reason for all this is the relativedistance of the two events. At 0.72astronomical units from the Sun, Venus’distance from Earth varies from roughly0.28 AU from Earth at inferior conjunctionto 1.72 at superior. At superior conjunctionit is therefore some six times the distance,and one-sixth the apparent size, as atclosest approach. Its apparent speed isslower still, as it is now moving “with”the Sun, whereas at inferior conjunctionit is going in the opposite direction.But some conjunctions are moresuperior than others. While this June’soccultation was unobservable in theconventional sense, in this day and agesuch events are easily available to thevirtual observer. Idle thought experimentscan actually be tested. Equipped with thesoftware program Guide 6.0, I “observed”long series of Venus conjunctions to testand confirm some conclusions I hadalready reached. And, by golly, logic winsout yet again.All Venus watchers become awareof the eight-year periodicity of itsapparitions. As noted by theMesopotamians, Mayans, and others, ittakes almost exactly eight years (actually,eight years minus about 2.3 days) forVenus to orbit the Sun thirteen times. Inthat time, Venus “laps” Earth five times(synodic revolutions), after which thetwo planets return to a very similaralignment as their “starting point” eightyears previous. There are therefore fivemorning and evening apparitions of Venusthat repeat themselves to a high degreeof similarity over the course of a humanlifetime.An even more exact periodicity of152 synodic revolutions per 243 yearscomes into play when considering longtermcycles. Why 243? In that time therehave been 30 eight-year cycles, meaningthe deficit of 2.3 days from each will nowhave amounted to roughly 69 days. Twomore 584-day synodic cycles of Venusamount to three years plus about 72 days,eliminating that deficit more efficientlythan a modern government. The “interest”of three days is attributable to Earth’sprecession, which in 243 years would havecompleted about 1% of a cycle.As an aside, my dear friend the lateFather Lucian Kemble, a self-proclaimed“Fibonacci nut” who pondered theFibonacci sequence in the relationshipbetween 5 synodic cycles to 8 Earth yearsto 13 Venus orbits, would have beenamused to note that the periods of 8 and243 years can be represented in exponentialnotation as 2 3 and 3 5 !In a 243-year cycle there are, in thecurrent era, two pairs of Venus transits,each at eight-year intervals and separatedby more than a century. One pair willoccur in June at the descending node, theother pair in December at the ascending.(Transits can also act alone, but therehasn’t been a singleton since 1396, norwill there be another until 3089. Indeed,in the long term — the 9000 years from2000 bce to 7000 ce were reviewed —single transits are almost as common aspairs. The fascinating pattern of theseevents is best left for a future article.)But shouldn’t transits andoccultations be inter-related? Given the13:8 periodicity, after four Earth yearsVenus will have completed 6.5 orbits, or2.5 synodic revolutions. As in therelationship between solar and lunareclipses, Venus should be at one node ofits orbit at the transits, and the oppositeat the midway points. This explains whyVenus was occulted in 2000, almost fouryears to the day before the transit.As I pondered all this it occurred tome that from our perspective Venus shouldalso stick about six times closer to theecliptic when at superior conjunction.Accordingly, there should be about sixtimes as many occultations of Venus bythe Sun as there are transits. (The samethought occurred independently to MichaelWatson, who posted his similar findingson the RASCals Discussion List in mid-June.) I examined every superiorconjunction of Venus between 1960 and2060 on Guide (using geocentriccoordinates), and the pattern emergedas shown in the table.Occultations of Venus:Transits of Venus:Date Midpoint Duration Date Midpoint Duration1976 June 18 01:26 UT 8.3 hours1984 June 15 19:58 28.11992 June 13 14:34 36.82000 June 11 09:14 42.0 2004 June 8 8:21 UT 6.2 hours2008 June 9 03:41 44.8 2012 June 6 1:31 UT 6.72016 June 6 21:52 45.72024 June 4 16:17 44.62032 June 2 10:32 41.42040 May 31 04:30 35.72048 May 28 22:06 25.5One can readily see the 8 year minus~ 2.3 day periodicity. The first occultationoccurs near the north limb of the Sun.The events grow in duration as they262JRASC December/ décembre 2000

ecome progressively more central untilthe one in 2016, then recede as thesouthward progression continues. On2056 May 26, Venus just grazes the southlimb of the Sun without being occulted,thus ending the series. Indeed, the seriesresembles occultation patterns of theMoon against a given star, or for thatmatter the well-known Saros cycle ofsolar and lunar eclipses.Significantly, the above occultationsof Venus are the only ones that occur inthe century under study. There are norandom occultations, just this series often surrounding the two transits.Conjunction Junction is in eastern Taurus,where all twelve events occur, graduallyregressing westward into the horns of theBull. And whereas the two transits occurat the descending node, all of theoccultations occur at the ascending.I examined several further serieswith virtually identical results. The transitpair of 2117 December 11 and 2125December 8 is surrounded by a series ofnine occultations between 2081 December19 and 2145 November 30. And the transitpair of 2247 June 11 and 2255 June 9 issurrounded by another series of tenoccultations between 2219 June 21 and2291 June 1. Note that each of these datesin the 23rd century occurs exactly 243years (plus about three days) after itsanalogue in the current series.Even though this year’s occultationis over, visually you didn’t miss a thing;it was unobservable. Moreover, thoughtexperiments and computer observationssimply aren’t subject to real time and canbe virtually recreated at the leisure of theuser. Better yet, as with previous eventsin this series, an occultation is alwaysfollowed by an inferior conjunction whichis extremely favourable to northernobservers. At the upcoming inferiorconjunction of 2001 March 30, Venus willpass a full eight degrees north of the Sun,slightly better than the conjunctions of1977, 1985, and 1993 described elsewherein this issue of JRASC by Father LucianKemble. Now that will be something youcan get out and see for yourself, in bothmorning and evening twilight, and, withproper care, all day long!ReferencesChapman, David M. F. 1986, “Recurrent Phenomenaof Venus and the Venus/Earth Orbital Resonance,”JRASC 80, pp. 336-343Chapman, David M. F. 1986, “Why Do Transits ofVenus Occur in Pairs?” Nova Notes, May/JuneKemble, Fr. Lucian, OFM “Daytime Observationsof Venus at Inferior Conjunction,” JRASC (currentissue)Krupp, E. C. 1996, “Falling for the Evening Star,”Sky & Telescope, MayMeeus, Jean. 1997, “Planetary motions: approximateperiodicities,” Mathematical Astronomy Morsels,Willmann-Bell, Inc.Meeus, Jean. 1989, Transits, Willmann-Bell, Inc.The assistance of Dave Chapman, RussSampson, and Michael Watson is gratefullyacknowledged.Past President of the Edmonton Centre RASC,Bruce McCurdy is also the resident “semipro”astronomer at the Edmonton Space &Science Centre’s Public Observatory, wherehe has provided volunteer service for the past14 years and has enjoyed paid employmentfor the past five summers. He has anomnivorous appetite for all things astronomical,be they observational or theoretical in nature.His friends consider Bruce to be somethingof an oddity in his own right.Scenic VistasBeyond the Orion Nebulaby Mark Bratton, Montreal Centre (mbratton@generation.net)Showpiece deep-sky objects such asthe Andromeda Galaxy, the HerculesCluster, or the Orion Nebula dominatethe constellations in which they appear,often to the exclusion of all else in theirrespective regions of the sky. The situationis understandable; after all, who can resistthe allure of M13 or the brilliant, complexstructure of M42?But digging a little deeper into starcharts and into the sky itself will oftenbring the observer face to face with marvelsevery bit as fascinating as these celestialwonders. The constellation of Orion ishome to dozens of deep-sky challengessuitable for amateur-sized telescopes;two of these targets will be discussed inthe present article.One of the more fascinating aspectsof “real-time” deep-sky astronomy iscomparing the results of visual observationto those of imaging (whether byastrophotography or CCD). It has beenmy experience that neither technique issuperior to the other; each revealsimportant information about the objectunder study. Observations of NGC 1999and NGC 2194 are a case in point.Located little more than one degreesouth-southeast from the Orion Nebula,NGC 1999 is surprisingly little knownamongst amateur astronomers, but thiscomplex object is fascinating to observe.Classified as an emission-reflection nebula,it features a prominent triangularabsorption region, so the term “darknebula” could also be added to itsdescription. The T Tauri-type variablestar V380 is presumed to be the excitingstar of the nebula, but in the Palomar SkySurvey photograph at bottom right, thelong exposure brings out the nebula atDecember/ décembre 2000 JRASC263

the expense of the star. My observationof this nebula (illustrated on the top left)occurred on October 7–8, 1994 and revealsthe star as well as a bright, crescentshapednebulosity that surrounded thestar on all sides except to the southwest.Here, my notes indicate that a dark zonewas visible. This dark zone is shown clearlyin the Palomar image at bottom left. Whilethe drawing and the photo have somevague similarities, it is interesting to notewhat an astrophoto (albeit overexposed)reveals as compared to a visual observation.NGC 2194 is a small, rich open clusterlocated in the northeastern region ofOrion. Its isolated location, far from anybright star, might make it difficult tolocate, but under very dark skies the stars73 and 74 Orionis may be faintly visible,leading observers to the open cluster.The visual observation (top right)was made on the evening of February25–26, 1995 from Sutton, Quebec on anight when stars to magnitude +5.5 werevisible at the north celestial pole. Mynotes describe the cluster as small, thoughbright and fairly compressed and wellisolated from surrounding field stars.Resolved stars were in the range ofmagnitude +12 to +14, and I countedabout forty stars as being individuallyvisible. My notes describe the cluster as“wasp-waisted,” appearing concave towardsthe center. A soft glow of unresolved starsindicates the richness of the cluster.When we study the Palomar SkySurvey image (bottom right), a chain ofstars is clearly visible running due eastwest:the “wasp-waist.” In the photo, starsto about magnitude +18 are visible, butotherwise there is generally good agreementbetween the photo and the structure Isketched at the eyepiece.With patience and a light touch, anyobserver can make an accurate sketch ofthe view through a telescope. And thefun part comes later when we comparewhat the eye sees to what the camerareveals.Mark Bratton, who is also a member of theWebb Society, has never met a deep sky objecthe did not like. He is one of the authors ofNight Sky: An Explore Your World Handbook.Visual sketches (above) and Digitized Sky Survey images (below) of NGC 1999 (left)and NGC 2194 (right).264JRASC December / décembre 2000

Index to Volume 94, 2000TitlesAbstracts of Papers Presented at the 1999 Annual Meeting ofthe MIAC/CCMI Held in Edmonton, Alberta, October 23,1999, Feb., 23Abstracts of Papers Presented at the 2000 CASCA Annual MeetingHeld at the University of British Columbia, Vancouver, May25 to May 28, Dec., 246Abstracts of Papers Presented at the 2000 RASC General AssemblyHeld in Winnipeg June 30 to July 2, 2000, Aug./Oct., 179Annual Meeting of the Meteorite and Impacts Advisory Committeeto the Canadian Space Agency, The 1999, Alan R. Hildebrand,Feb., 22A Secondary Survey of the Attitudes of University Students toAstrology and Astronomy, Michael M. De Robertis andPaul A. Delaney, Jun., 112Astronomical Refraction and the Equinox Sunrise, Russell D.Sampson, Feb., 26Conjunctions of Jupiter and Saturn, Donald V. Etz, Aug./Oct.,174Period Changes in the SX Phoenicis Stars. I. BL Camelopardalisand DY Pegasi, R. Melvin Blake, Houman Khosravani, andPaul A. Delaney, Jun., 124Photoelectric Magnitude Measurements of Mars Made Duringthe 1998-2000 Apparition, Richard W. Schmude Jr., Dec.,241Space Mirror Experiment: A Potential Threat to Human Eyes,James G. Laframboise and B. Ralph Chou, Dec., 237Star Patterns on the Aztec Calendar Stone, Robert S. McIvor,Apr., 56Théorie sur le cadran solaire bifilaire vertical déclinant, DominiqueCollin, Jun., 95AuthorsAttas, Michael, A Lamplighter Moment: Astronomy throughthe Windshield, Apr., 51Attwood, Randy, President’s Corner, Feb., 3President’s Corner, Apr., 42President’s Corner, Jun., 78Attwood, Randy, Observer’s Report: The November 15, 1999Transit of Mercury, Aug./Oct., 154Bahcall, John N., How the Sun Shines, Dec., 219Barkhouse, Wayne A., Editorial, Aug./Oct., 148Editorial, Dec., 208Barkhouse, Wayne A. and Chris R. Burns, Improving the Teachingof Astronomy 101 Through Tutorials, Dec., 252Blake, R. Melvin, Houman Khosravani and Paul A. Delaney,Period Changes in the SX Phoenicis Stars. I. BL Camelopardalisand DY Pegasi, Jun., 124Bogan, Larry, Midway from the Equator to the North Pole, Apr.,48Bratton, Mark, Scenic Vistas: Beyond the Orion Nebula, Dec.,263Scenic Vistas: Galaxy Groups in Leo, Feb., 39Scenic Vistas: North of Spica, Apr., 73Scenic Vistas: Mysteries in Cepheus, Aug./Oct., 194Scenic Vistas: Some Southern Globulars, Jun., 135Broderick, Bill, A Candle in the Dark, Dec., 257Chapman, David M. F., Reflections: Calendrical Conundrumsand Cosmic Chaos, Feb., 17Reflections: Gian Domenico Cassini — or is it Jean-Dominique?, Jun., 91Reflections: Henry Draper, Aug./Oct., 171Reflections: Jan Hendrik Oort — Swirling Galaxies andClouds of Comets, Apr., 53Reflections: New Year’s Day, Dec., 232Chapman, David M. F., Gravity without Forces, Aug./Oct., 168Collin, Dominique, Théorie sur le cadran solaire bifilaire verticaldéclinant, Jun., 95De Robertis, Michael and Paul A. Delaney, A Second Survey ofthe Attitudes of University Students to Astrology andAstronomy, Jun., 112Dymond, Garry, The St. John’s Centre and the Marine InstitutePlanetarium, Jun., 86Earl, Michael A., The Space Surveillance Research and AnalysisLaboratory, Dec., 213Etz, Donald V., Conjunctions of Jupiter and Saturn, Aug./Oct.,174Gagné, Laura, Expanding Their Universe: Helping OntarioTeachers With Astronomy, Feb., 30Garrison, Robert F., President’s Corner, Aug./Oct., 146Garrison, Robert F., President’s Corner, Dec., 206Hall, Cathy L., For the Love of Meteors, Feb., 9Hay, Kim, Society News/Nouvelles de la société, Aug./Oct., 184Hildebrand, Alan R., The 1999 Annual Meeting of the Meteoriteand Impacts Advisory Committee to the Canadian SpaceAgency, Feb., 22Huziak, Richard, Observing Geostationary Satellites, Feb., 14Laframboise, James G. and B. Ralph Chou, Space Mirror Experiment:A Potential Threat to Human Eyes, Dec., 237Kelly, Patrick, From the Associate Editor, Apr., 43Kemble, Fr. Lucian J., OFM, (with comments by David M. F.Chapman), A Lamplighter Moment: Daytime Observationsof Venus at Inferior Conjunction, Dec., 229Kulik, Christine, La Météorite de St-Robert, Feb., 16Kulik, Christine, Last Light, Jun., 90Kulik, Christine, The Winds of Time, Apr., 52Mackie, Guy, At the Eyepiece: Cygnus Delights, Jun., 133Mackie, Guy, At the Eyepiece: Royal Reflections, Dec., 259December / décembre 2000 JRASC265

Malicki, Chris, The November 15 th Transit of Mercury, Feb., 7Markov, Paul, The Observing Logbook, Aug./Oct., 157McCausland, Phil, Winnipeg: The RASC General Assembly for2000, Aug./Oct., 186McCurdy, Bruce, Orbital Oddities: Conjunction Junction, Dec.,261McDermott, John, Using the Observer’s Handbook, Aug./Oct.,190McIvor, Robert S., Star Patterns on the Aztec Calendar Stone,Apr., 56Milan, Wil, The Truth about Astroimaging, Aug./Oct., 165Moore, Patrick, Transient Phenomena on the Moon, Dec., 228O’Neil, Joseph G., Fast Polar Alignment, Jun., 88Pulley, Harry C., Getting Ready for Solar Maximum, Jun., 83Pulley, Harry C., Close to Home: Observing Planets Early, Aug./Oct.,192Sage, Leslie J., Second Light: Detecting Other Planets, Feb., 19Second Light: “Of pale kings and pyramids”, Dec., 235Second Light: Thunderstorms on Jupiter, Apr., 54Second Light: Weighing the Universe, Aug./Oct., 172Second Light: X-ray Background Explained, Jun., 93Sampson, Russell D., Astronomical Refraction and the EquinoxSunrise, Feb., 26Schmude, Richard W., Jr., Photoelectric Magnitude Measurementsof Mars Made During the 1998-2000 Apparition, Dec., 241Silverman, Barbara, The History of Astronomy: Unsung Heroes,Feb., 37The History of Astronomy: Myths and Legends, Apr., 70Stuart, Douglas, Observing Programs, Jun., 137Turner, David, From the Editor, Feb., 2From the Editor, Jun., 80Vaduvescu, Ovidiu, EuRo Eclipse 99, Feb., 32Watson, Michael, Robert May and David Lane, General Assembly2000 Photo Gallery, Aug./Oct., 161Whitehorne, Mary Lou, National Council Report - 2000 GeneralAssembly, Aug./Oct., 188Whitehorne, Mary Lou, Nova Scotia Teachers Meet an AstronomicalChallenge, Jun., 130Whitehorne, Mary Lou, Sharing the Astronomical Adventure,Aug./Oct., 182Whitman, Alan, At The Eyepiece: The All Splendours, No FuzziesObserving List (Part 3 of 4), Feb., 35At the Eyepiece: The Complete All Splendours, No FuzziesObserving List, Apr., 65DepartmentsAcross The RASC:A Candle in the Dark, Dec., 257Astrocryptic: Feb., 40, Apr., 76, Jun., 143, Aug./Oct., 204, Dec.,268Astronomical Society of the Pacific Awards, The, Dec., 256EuRo Eclipse 99, Feb., 32National Council Report - 2000 General Assembly, Aug./Oct., 188Observing Programs, Jun., 137Scenic Vistas: Galaxy Groups in Leo, Feb., 39Scenic Vistas: North of Spica, Apr., 73Scenic Vistas: Some Southern Globulars, Jun., 135Society News: Apr., 62, Jun., 132, Aug./Oct., 184, Dec., 255Using the Observer’s Handbook, Aug./Oct., 190Winnipeg: The RASC General Assembly for 2000, Aug./Oct., 186Columns:Ask Gazer, Feb., 34, Apr., 64, Aug./Oct., 191At The Eyepiece: All Splendours, No Fuzzies Observing List(Part 3 of 4), Feb., 35At The Eyepiece: The Complete All Splendours, No FuzziesObserving List, Apr., 65At The Eyepiece: Cygnus Delights, Jun., 133At The Eyepiece: Royal Reflections, Dec., 259Close to Home: Observe Planets Early, Aug./Oct., 192History of Astronomy: Unsung Heroes, Feb., 37History of Astronomy: Myths and Legends, Apr., 70Orbital Oddities: Conjunction Junction, Dec., 261Reflections: Calendrical Conundrums and Cosmic Chaos, Feb.,17Reflections: Jan Hendrik Oort - Swirling Galaxies and Cloudsof Comets, Apr., 53Reflections: Gian Domenico Cassini, Jun., 91Reflections: Henry Draper, Aug./Oct., 171Reflections: New Year’s Day, Dec., 232Scenic Vistas: Mysteries in Cepheus, Aug./Oct., 194Scenic Vistas: Beyond the Orion Nebula, Dec., 263Second Light: Detecting Other Planets, Feb., 19Second Light: Thunderstorms on Jupiter, Apr., 54Second Light: X-ray Background Explained, Jun., 93Second Light: Weighing the Universe, Aug./Oct., 172Second Light: “Of pale kings and pyramids”, Dec., 235Correspondence: Apr., 44, Jun., 81, Aug./Oct., 149, Dec., 209Education Notes:Expanding Their Universe: Helping Ontario Teachers WithAstronomy, Feb., 30Improving the Teaching of Astronomy 101 Through Tutorials,Dec., 252Nova Scotia Teachers Meet an Astronomical Challenge, Jun.,130Sharing the Astronomical Adventure, Aug./Oct., 182Editorial: Aug./Oct., 148, Dec., 208Feature Articles:A Lamplighter Moment: Astronomy Through the Windshield,Apr., 51A Lamplighter Moment: Daytime Observations of Venus atInferior Conjunction, Dec., 229Fast Polar Alignment, Jun., 88For the Love of Meteors, Feb., 9Gravity without Forces, Aug./Oct., 168General Assembly 2000 Photo Gallery, Aug./Oct., 161Getting Ready for Solar Maximum, Jun., 83How the Sun Shines, Dec., 219266JRASC December / décembre 2000

La Météorite de St-Robert, Feb., 16Last Light, Jun., 90Midway from the Equator to the North Pole, Apr., 48November 15 th Transit of Mercury, The, Feb., 7Observer’s Report: The November 15, 1999 Transit of Mercury,Aug./Oct., 154Observing Geostationary Satellites, Feb., 14Observing Logbook, The, Aug./Oct., 157St. John’s Centre and the Marine Institute Planetarium, The,Jun., 86Space Surveillance Research and Analysis Laboratory, The, Dec.,213Transient Phenomena on the Moon, Dec., 228Truth about Astroimaging, The, Aug./Oct., 165Winds of Time, The, Apr., 52From the Associate Editor: Apr., 43From the Editor: Feb., 2, Jun., 80From the Past: Feb., 8, Apr., 60, Jun., 123, Aug./Oct., 148, Dec.,234News Notes: Feb., 4, Apr., 46, Jun., 81, Aug./Oct., 150, Dec., 210Obituaries: Isabel K. Williamson (1908-2000), Aug./Oct., 201President’s Corner: Feb., 3, Apr., 42, Jun., 78, Aug./Oct., 146,Dec., 206Research Papers: see TitlesReview of Publications:AURA and its U. S. National Observatories, by Frank K. Edmondson,Aug./Oct., 196Cambridge Concise History of Astronomy, The, edited by MichaelHoskin, Aug./Oct., 198Elegant Universe, The, by Brian Greene, Aug./Oct., 197Erratum: Observing Variable Stars: A Guide for the Beginner,by David H. Levy, Jun., 142From White Dwarfs to Black Holes: The Legacy of S. Chandrasekhar,edited by G. Srinivasan, Jun., 141Magnificent Universe, by Ken Croswell, Jun., 139Observing Variable Stars: A Guide for the Beginner, by DavidH. Levy, Apr., 74Our Cosmic Origins: From the Big Bang to the Emergence ofLife and Intelligence, by Armand Delsemme, Aug./Oct.,198Sky Atlas 2000.0, by Wil Tirion and Roger Sinnott, Jun., 139Solar Corona, The, by Leon Golub and Jay M. Pasachoff, Aug./Oct.,200December / décembre 2000 JRASC267

Astrocryptic Answersby Curt Nason, Moncton CentreAnswers to AstroCryptic #8268JRASC December / décembre 2000

THE ROYAL ASTRONOMICAL SOCIETY OF CANADANATIONAL OFFICERS AND COUNCIL FOR 2000-2001/CONSEIL ET ADMINISTRATEURS NATIONAUXHonourary PresidentPresident1st Vice-President2nd Vice-PresidentSecretaryTreasurerRecorderLibrarianPast PresidentsEditor of JournalEditor of Observer’s HandbookEditor of Beginner’s Observing GuideJack Locke, Ph.D., OttawaRobert Garrison, Ph.D., TorontoRajiv Gupta, Ph.D., VancouverPeter Jedicke, LondonKim Hay, KingstonMichael S. F. Watson, Unattached memberPeter Jedicke, LondonColin Haig, HamiltonRandy Attwood, Toronto, and Douglas P. George, M. Eng. B.A.Sc., OttawaWayne Barkhouse, TorontoRajiv Gupta, Ph.D., VancouverLeo Enright, KingstonExecutive Secretary Bonnie Bird, M.L.Sc., 136 Dupont Street, Toronto, ON, M5R 1V2 (Telephone: 416-924-7973)CENTRE ADDRESSES/ADRESSES DES CENTRESCalgaryc/o Calgary Science Centre, P. O. Box 2100, Station “M”, Loc #73, Calgary,AB, T2P 2M5Charlottetownc/o 38 Mt. Edward Road, Charlottetown, PE, C1A 5S2Edmontonc/o Edmonton Space & Sciences Centre, 11211 - 142 St., Edmonton, AB, T5M4A1HalifaxP. O. Box 31011, Halifax, NS, B3K 5T9HamiltonP. O. Box 1223, Waterdown, ON, LOR 2HOKingstonP. O. Box 1793, Kingston, ON, K7L 5J6Kitchener-Waterlooc/o Peter Daniel, 36 Talbot Street, Apt. 101, Kitchener, ON, N2M 2A9LondonP. O. Box 842, Station B, London, ON, N6A 4Z3Monctonc/o 66 Meadowbank Avenue, Saint John, NB, E2K 2C6MontrealP. O. Box 1752, Station B, Montréal, QC, H3B 3L3Centre Francophone de MontréalC. P. 206, Station St-Michel, Montréal, QC, H2A 3L9NiagaraP. O. Box 4040, St. Catharines, ON, L2R 7S3OkanaganP. O. Box 20119 TCM, Kelowna, BC, V1Y 9H2OttawaP. O. Box 33012, 1974 Baseline Road, Nepean, ON, K2C OEOQuébec2000, boul. Montmorency, Québec, QC, G1J 5E7ReginaP. O. Box 20014, Cornwall Centre, Regina, SK, S4P 4J7St. John’sc/o 206 Frecker Drive, St. John’s, NF, A1E 5H9Sarniac/o Jim Selinger, 160 George Street, Sarnia, ON, N7T 7V4SaskatoonP. O. Box 317, RPO University, Saskatoon, SK, S7N 4J8Thunder Bayc/o 135 Hogarth Street, Thunder Bay, ON, P7A 7H1Torontoc/o Ontario Science Centre, 770 Don Mills Road, Don Mills, ON,M3C 1T3Vancouverc/o Gordon Southam Observatory, 1100 Chestnut Street, Vancouver, BC, V6J 3J9Victoriac/o Bill Almond, 354 Benhomer Drive, Victoria, BC, V9C 2C6Windsorc/o Frank J. Shepley, 344 South Middle Road, R.R. # 2, Maidstone, ON, NOR 1K0WinnipegP.O. Box 2694, Winnipeg, MB, R3C 4B3

Publications and Products ofThe Royal Astronomical Society of CanadaObserver’s Calendar — 2001This calendar was created by members of the RASC. All photographs weretaken by amateur astronomers using ordinary camera lenses and smalltelescopes and represent a wide spectrum of objects. An informative captionaccompanies every photograph.It is designed with the observer in mind and contains comprehensiveastronomical data such as daily Moon rise and set times, significant lunar andplanetary conjunctions, eclipses, and meteor showers. The 1998, 1999, and 2000editions each won the Best Calendar Award from the Ontario Printing andImaging Association (designed and produced by Rajiv Gupta).Price: $14.95 (members); $16.95 (non-members)(includes taxes, postage and handling)The Beginner’s Observing GuideThis guide is for anyone with little or no experience in observing the night sky. Large, easy to readstar maps are provided to acquaint the reader with the constellations and bright stars. Basicinformation on observing the moon, planets and eclipses through the year 2005 is provided. Thereis also a special section to help Scouts, Cubs, Guides and Brownies achieve their respectiveastronomy badges.Written by Leo Enright (160 pages of information in a soft-cover book with otabinding which allowsthe book to lie flat).Price: $15 (includes taxes, postage and handling)Promotional ItemsThe RASC has many fine promotional items that sport the National Seal.Prices include postage and taxes. Included are a Cloth Crest (size 11cm withthe background white and the stitching in royal blue - $11), Lapel pins (blue,white, and silver - $5), Golf shirts (white, available in small and medium - $24),Stickers (size 7.5cm, blue with white overlay - $1 each or 2 for $1.50), Thermalmugs (in blue and white - $5.50), Toques (Black with Yellow lettering - $17),Key chains (Clear arcylic and Blue/white - $2.50).Shop On-Line at www.store.rasc.caSend cheque or money order to: RASC, 136 Dupont St., Toronto, ON, M5R 1V2 CanadaPlease allow 6-8 weeks for delivery. Orders outside Canada please remit in U.S. Funds.Major credit cards accepted. Call the National Office toll-free at 1-888-924-7272 to place your order.(copies of these publications may also be available directly from your local Centre)