july 2011 - Astronomical Society of Southern Africa

astronomyjhb.co.za

july 2011 - Astronomical Society of Southern Africa

july 2011

monthly newsletter of the johannesburg centre of assa

Total Lunar Eclipse, 15 June 2011

(Read further on page 4)

Photo: Gary Els, 10” Meade LX200, Canon 550D


canopus july 2011

page 2

8 June 2011: Space Shuttle and Space Station Photographed Together

Credit: NASA (http://apod.nasa.gov/apod/ap110608.html)

Do you want to advertise in

Canopus?

Canopus is widely read by more than 200 people every

month and has been in circulation for more than 30 years!

We have a number of options ranging from R110 to R385 per issue:

Rates for advertorial space To June 2012:

Full page, colour, inside cover R385

Half page, colour, inside cover R192.50

Full page, black and white R220

Half page, black and white R110

For more information please contact:

Heather Dalgleish: Alec Jamieson:

Cell: 082 417 6350

Cell: 082 654 5336

Email: hdalgleish@groupfive.co.za Email: alec.jamieson@telkomsa.net


Notice of Next Meeting – ASSA Johannesburg

canopus july 2011

Next meeting at Johannesburg Observatory, 18a Gill St, Observatory

Wednesday, 13 July 2011 at 7.30 pm

The Annual General Meeting of the ASSA Johannesburg Centre

(Read more on page 8)

Portfolio/Interest Name E-mail Contact Details

Chairman Gary Els gels@randwater.co.za 082 389 2250

Vice-Chairman Constant Volschenk starmanza@gmail.com 083 442 8169

Secretary, Membership

Secretary & Librarian

Alec Jamieson alec.jamieson@telkomsa.net 082 654 5336

Treasurer Heather Dalgleish hdalgleish@groupfive.co.za 082 417 6350 a/h

Viewing Officer Eric Brindeau eric.brindeau@gmail.com 083 698 8310

Curator of Instruments Michael Robins m.robins@ziehl-abegg.co.za 082 900 8371

Asst. Curator of Instruments Dave Hughes --- 082 412 6665

Public Relations Officer Sharon Tait labelconnection@mweb.co.za 082 455 0819

Webmaster Barend Botha bjbotha@yahoo.com 083 284 3496

Committee member Melvyn Hannibal Melvynh@iburst.co.za 011 435 6007

ASSA Johannesburg Mailing Lists

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announcements, activity reminders; including public viewing, meetings, star parties

and last minute changes.

To subscribe or unsubscribe, merely post a blank e-mail to the indicated addresses:

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Canopus Team

Editor: Eric Brindeau (eric.brindeau@gmail.com)

Advertising: Alec Jamieson (alec.jamieson@telkomsa.net)

Printing and Distribution: Alec and Sue Jamieson

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Chairman’s Chat

By Gary Els

What a wonderful sight, the Total Lunar Eclipse on the 15 th of June — I trust many of

our members were able to experience this heavenly phenomenon. The next day I

was watching BBC World News where they showed and interviewed people from

Johannesburg and around the world during the event, all so overwhelmed at the

beautiful red Moon. Those in Asia reported that the Moon had a more coppery

colour due to the volcanic ash in the atmosphere.

I spent the evening with a small group of friends in my observatory at home. Some

had never seen a Lunar Eclipse before, and their amazement was wonderful to see.

With my laptop attached to the camera on my telescope, we were able to see the

Moon “live” on the screen and with each image captured and reviewed all were

able to comment and make suggestions for the next exposure. It really gave a

participatory feeling about the whole event, which I thoroughly enjoyed.

Before eclipse day, I did some reading about Solar and Lunar eclipse stories

throughout the ages on the Astronomy Today website, in order to share with my

visitors, and I would like to mention just two of them from that site.

Ho and Hi, the Drunk Astronomers (2137 BCE)

page 4

Throughout the centuries, Chinese astronomers devoted substantial efforts towards

predicting eclipses. However, like all similar efforts prior to the Renaissance, this could only

be by empirical research. The earliest record of a solar eclipse comes from ancient

Chinese history since October 22, 2137 BCE. Ancient Chinese astronomy was primarily a

governmental activity. It was the astronomer's role to keep track of solar, lunar and

planetary motions and explain what they meant to the ruling emperor.

Eclipse observation in China around 1840: Astronomers calmly observe an eclipse and the servants,

terrified, prostrate themselves on the ground to placate the bad omen.

According to legend, the royal astronomers Ho and Hi dedicated too much of their time

to consuming alcohol and failed to predict a forthcoming eclipse. Traditionally, the solar


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eclipse recorded in the Shu Ching was regarded as having occurred the 3rd millennium

BCE. On the first day of the month, in the last month of autumn, the Sun and the Moon did

not meet (harmoniously) in Fang' ... so runs the text. The emperor became very unhappy

because, without knowing that there was an eclipse coming, he was unable to organize

teams to beat drums and shoot arrows in the air to frighten away the invisible dragon. The

Sun did survive, but the two astronomers lost their heads for such negligence. Since then, a

legend arose that no one has ever seen an astronomer drunk during an eclipse.

Now I wonder if the legend of drunken astronomers is still true today!!? Of cause on

eclipse night in the observatory, we were totally sober sipping a glass of wine.

Christopher Columbus' Eclipse (1504 CE)

After a long trip to the Americas in 1503, in his fourth voyage, Columbus was stranded on

the island of Jamaica. In principle, he managed to obtain provisions from the Caciques

natives in exchange for some trinkets and rubbish. As the months went by, novelty and

hospitality started to decrease and also the sailors became more aggressive with the

natives in order to obtain food. Then the native Jamaicans communicated to the Spanish

that they would not provide any more supplies.

Columbus became desperate with the

threat of famine and came up with an

ingenious plan. He checked his

Calendarium, which contained

predictions of lunar eclipses for several

years. In particular, it predicted a total

eclipse of the Moon on the Antilles on

February 29, 1504 CE. That evening, he

invited the Caciques on-board his

Capitana for a serious conversation. He

told them that they were Christians and

their God did not like the way they had

been treating them and would punish

the Indians with famine and pestilence

and, as a sign of dissatisfaction, he would darken the Moon. As soon as he said that, the

Earth's shadow started to cover the white disk. Terrified, the natives begged Columbus to

bring back the light.

He replied that he needed to consult his God. He shut himself in a cabin for nearly two

hours. Just before the end of totality, he reappeared and announced that God had

given his pardon, and would bring them back the Moon provided that the Christians were

given provisions. Immediately, the Moon reappeared. Astonished, the natives

immediately provided Columbus and his crew their needed provisions until they were able

to return to Europe.

With all the nonsense doing its rounds again on the internet, such as two suns will appear

in the night sky, it’s great to see real predictions being enjoyed by so many, and I hope

no one was manipulated as Columbus did in 1504 AD.

Gary

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Notes on the Monthly Meeting

By Melvyn Hannibal

The evening commenced with feedback from Gary Els about the dark-sky weekend

at Suikerbos Nature Reserve. He showed us some of his photos of the resort and some

he took through our 12" telescope.

Dave Blane gave us brief run down on his work with double stars, showing us photos

of his equipment, and extracts from various double star catalogues.

Constant Volschenk told us about the current night skies, and demonstrated the

eclipse on the 15th.

The main speaker was Jonny Rizos from the “South African

National Space Agency”. No, we are not going into

competition with NASA.

This local organisation is concerned with using satellites

that observe the Earth. The Facility is based at

Hartebeesthoek near Krugersdorp. The site was originally

set up by the Americans, and then passed to the CSIR. In

April this year SANSA was formed and given the use of the

site. This is a Radio facility. The data is used to follow urban

growth, land usage, and studies of that nature, and covers

a circular area from three degrees South of the equator.

This covers all of southern Africa.

Melvyn

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Right: Jonny Rizos, from SANSA (Photo: M Hannibal)

Late News Item — 25 June: ASSA website http://assa.saao.ac.za/ states “ASSA

constitution accepted”. The new draft constitution that has been accepted can be

seen at http://assa.saao.ac.za/resource/ASSAConstitutionRedraft2011-05-26.pdf

More information is expected to follow shortly on the consequences of the new

constitution on ASSA Centres and will be notified via ASSA Announce maillist, placed on

the website and in the next Canopus.

Alec Jamieson - Secretary

Upcoming Events

Friday, 1 July 2011

Public viewing

Venue: Johannesburg Observatory, 18a Gill St, Observatory

Starting time: 7:00pm


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Saturday, 2 July 2011

Dark sky viewing from Suikerbosrand (members only)

Venue: Suikerbosrand Nature Reserve, outside Heidelberg

Time: gates close at 4pm

Bring: chairs, food and drink (bring and braai)

Contact: Constant - starmanza@gmail.com (have your car registration available)

Wednesday, 13 July 2011

The Annual General Meeting of the ASSA Johannesburg Centre

Members will be able to nominate candidates for election to the Committee for

the year ending June 2012 – read more on page 8

Venue: Telescope Lecture Room, JHB Observatory, 18a Gill St, Observatory

Starting time: 7:30pm

Saturday, 23 July 2011 (RSVP by 15 July)

ESSA/ASSA/ATM Star party - Exploration Society of Southern Africa (ESSA),

Astronomical Society of Southern Africa (ASSA), Amateur Telescope Makers (ATM)

Venue: Paul's farm, Magaliesburg, +/- 2 hour drive from Joburg or Pretoria

(detailed directions and instructions will be sent by e-mail closer to the time)

Time: it is advisable to arrive at about 15h00

Cost: R30 for ESSA/ASSA/ATM members, R50 for non-members (children and

people bringing telescopes free)

Accommodation: camping available for diehards at R20 for the night

Viewing opportunity: ASSA Jhb will be taking the 12" Meade to the event and

members will have a chance so see how it performs under a dark sky

RSVP: by 15 July, Simon Donally: donallys2@yahoo.fr

Thursday, 28 July 2011

Science in Science Fiction? Are Sci-Fi Futures far-fetched fantasy or feasible fact?

Venue: Auditorium, Sci-Bono Discovery Centre, Miriam Makeba Street

between Jeppe & President, Newtown, Joburg (secure lit parking available)

Time: 6:30 for 7:00 pm

RSVP: speaktoascientist@sci-bono.co.za

Contact: Refilwe Pico (011 639 8448) for more information

Friday 29 to Sunday 31 July 2011

West Rand Astronomy Club Annual Star Party: all are welcome

Venue: Mountain Sanctuary Park, Magaliesberg (private nature reserve, about

120km north-west of Johannesburg and 90km west of Pretoria)

Accommodation: options are chalets, log cabins or camping - telescopes will

be set up in an open field between campsites 14 & 16

Bookings: please contact Mountain Sanctuary Park @ Tel: (014) 534-0114

(08H00-17H00, 7 Days a week), e-mail: owen@mountain-sanctuary.co.za, web:

www.mountain-sanctuary.co.za

Contact: Kenny Neville on 082 335 1983, email: kenny@wrac.org.za

Program & further details: visit www.wrac.org.za

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Monday 3 to Friday 7 October 2011

62nd International Astronautical Congress

Venue: Cape Town International Convention Centre

Visit: http://iac2011.com for more information

ASSA JHB AGM: Notice of Meeting – 13 July 2011

The Annual General Meeting of Members of the ASSA Johannesburg Centre will be

held in the Telescope Lecture Room at the Johannesburg Observatory on

Wednesday 13 th July 2011, commencing at 7:30 pm.

Agenda

1. Notice of meeting.

2. Welcome

3. Attendance / Apologies.

4. Confirmation of the previous minutes.

5. Office Bearers’ reports for the year ended 30th June 2011:

5.1. Chairman’s report, Gary Els.

5.2. Treasurer's report, Heather Dalgleish.

5.3. Membership Secretary and Librarian’s report, Alec Jamieson.

5.4. Curator of Instruments report, Gary Els in the absence of Michael Robins.

5.5. Observing report, Eric Brindeau.

5.6. Astro-photography, Gary Els.

6. Awards and prize giving.

7. General.

8. Final nominations for the election of Committee members.

9. Voting.

10. Results of the Committee election.

11. Closure.

12. Snacks and refreshments during vote counting.

ASSA JHB Committee Election: Call for Nominations

By Alec Jamieson

Election of the 2011/2012 committee will take place at the Annual General Meeting to

be held on 13th July 2011, and nominations of candidates for election to the committee

are requested.

Nominations must be in writing, and received by the Secretary by 11th July 2011:

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by hand;

or by post to P. O. Box 412323, Craighall, 2024;

or by e-mail to alec.jamieson@telkomsa.net ;

or by fax to 011 886 7288. Note: this is a manual fax, please phone first.

Late nominations will be accepted at the AGM at the discretion of the Electoral Officer

and the names of late nominees will not appear on the voting form.

There is no prescribed nomination form. For guidance, a typical nomination would take

the form shown below.

I, ............................................. nominate ......................................... for election to the

Name printed Name printed

2011/2012 ASSA Johannesburg Centre Committee.

Seconded .................................... ................................................. ..............................

Name printed Signature Date

Accepted .................................... ................................................. ..............................

Name printed Signature Date

For a nomination to be valid, all names appearing on a nomination must be names of

members in good standing with the Centre.

In the case of e-mail nominations, the Secretary will confirm the nominations

telephonically, using telephone numbers recorded in the membership database.

To encourage wider participation in the committee, more than the minimum 7 members

may be elected. A committee must consist of at least a chairman, vice-chairman,

secretary, treasurer and 3 other members. The newly elected committee chooses the

chairman by consensus, and thereafter the chairman leads the discussion in the

allocation of other responsibilities. For this reason it is not possible to nominate candidates

for election to a particular position on the committee.

New ideas are vital to any organisation, so recently joined members should not feel

excluded from participating in the ASSA Jhb Centre Committee.

Alec Jamieson, Secretary.

New Members

The Committee would like to welcome the following new members to the ASSA

Johannesburg Centre:

Member No Name

1201 Norman Leibowitz

1202 Kerry McArthur

page 9


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M41 – Your Best Friend

By Magda Streicher

Canis Major is a special constellation because of its shape and the impression it creates

for a star-lover. It houses bright and outstanding objects and, of course, the brightest star,

Sirius.

NGC 2287, also known as Messier 41, appears to be hiding itself under the belly of the

doglike figure, like a bunch of fleas, about 4º south of Sirius. This beautiful cluster of

approximately 100 stars, which can be seen with the naked eye and partly resolved

using binoculars, is moving away from us at about 34 km per second and is said to be

about 24 light years across and 2 300 light years away.

This is one of the few deep sky objects to have been recorded by the ancients: it was

mentioned by Aristotle in 325 BC. It is one of the delights of the sky, with the grouping

reminding me of a lovely flower opening its petals in clear curls and curved lines. Two

rust-coloured stars, magnitude 6.8 and 7.3, remind me of pollen threads flowing out of a

central crown consisting of a semi-circle of bright members. A swarm of faint stars covers

the cluster like powder dust with a few dark patches between chains of faint stars. The

magnitude 6 star 12 Canis Majoris shares the field of view towards the south-east.

M41 – Like a flower opening its petals in clear curls and curved lines (Sketch: Magda Streicher)

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Name Object RA: DEC: Magnitude Size

M41 Open Cluster 06h41m.2 -20 o 44’52” 4.5 38.0’

It is easy to make friends with fellow astronomers, as they are usually friendly and

winsome people. Eric Brindeau, who was so helpful to me and did such an outstanding

job at Canopus, became such a friend. Although, sadly, he will be leaving his position at

the end of June, he remains a friend to me and to everyone else at Canopus.

— Thanks Magda! Your articles have inspired me to find new and exciting objects. I wait

in anticipation for your forthcoming book — Editor

Magda Streicher

magdalena@mweb.co.za

Magda—a past President of ASSA—is a passionate deep-sky observer and views

from excellent, dark skies on a farm close to the Zimbabwe border. Her fascination

in the stars goes back to childhood and over the past 15 years has contributed

greatly to visual astronomy in SA, helping to motivate others to observe and record

deep-sky objects. Using 12” and 16” Schmidt-Cassegrain telescopes, she hunts

down and sketches these faint fuzzies, sharing her interest through regular talks and

articles. She contributes to various deep sky sections in SA as well as publications

like Canopus and Deep Sky Delights, her regular deep sky column in MNASSA

(Monthly Notes of the Astronomical Society of SA). Magda is currently working on

her book “Astronomy Delights”, which she plans to finish towards the end of year.

Satellite Phone Dish to be Turned into Telescope

Submitted by Eric Brindeau

http://www.irishtimes.com/newspaper/ireland/2011/0510/1224296602827.html

The Irish Times - Tuesday, May 10, 2011: A 32-metre satellite dish originally used in the

1980s to take transatlantic calls from Europe to the US is to be reborn as a deep

space radio telescope.

The huge dish was originally constructed in Co Cork in 1984 but was retired in the

mid-1990s when new fibre-optic transatlantic cables were laid.

There are only a handful of these dishes remaining globally, many of which have

fallen into disrepair.

Right: Arek Pilat, a satellite engineer at Elfordstown

Earthstation, Midleton, Co Cork, with the former

telephone satellite dish which is to become a deep

space radio telescope available to students for

educational purposes.

Photograph: Gerard McCarthy (Irish Times)

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Yesterday at Elfordstown Earthstation, Midleton, Co Cork, Minister of State for

Research and Innovation Seán Sherlock announced a partnership between the

National Space Centre and Cork Institute of Technology (CIT) which will see the dish

start a new life as a telescope. The telescope will be capable of detecting a host of

cosmic phenomena including the emission of giant, slow moving hydrogen clouds,

the violent explosions of stars, eruptions of the solar surface and storms on Jupiter.

It will be the only 32m radio telescope available to primary students for educational

purposes in Europe.

Phase one of the project will see the telescope operational by the end of this

summer, with feeds available in September via the internet to primary and post

primary schools.

Phase two will occur in 2012 and will involve the refurbishment of the dish to enable it

to turn as it originally did and the installation of sensors and new receivers. The

project will be co-ordinated and operated by CIT under Dr Niall Smith, head of

research, and Blackrock Castle Observatory.

Dr Smith said this project will see a €10 million radio telescope brought back to life for

less than €10,000 thanks to the partnership between the National Space Centre and

CIT.

“It’s a great example of using world-class infrastructure in the most cost-effective

way to reach out into the community and to embed our growing scientific heritage

alongside our world-renowned culture.

“It will excite students in schools who will get to listen in on the radio signals from outer

space.

“It will be a test bed for engineering and science projects from primary through to

PhD.” The project will benefit education and skills training, and research and

development and provide incomparable hands-on training and research

opportunities for students from primary through to PhD level.

Mr Sherlock said the National Space Centre is already active in European Space

Agency (ESA) programmes including the Galileo Satellite Navigation Programmes.

“Ireland’s ESA membership has contributed to the development of a highly

knowledge-intensive industry sector with over 60 Irish technology companies having

secured ESA contracts worth over € 60 million since 2000.

“We expect this number to grow significantly in 2011,” the Minister added.

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ASSA JHB Dark Sky Weekend: 27-29 May 2011

By Antonio De Franca (Pretoria Centre member)

The Suikerbos Nature Reserve is situated in the Vredefort Dome area approximately 22km

southeast of Potchefstroom, near Venterskroon. This splendid area is declared a World

Heritage Site and it boasts a number of interesting treasures e.g. wildlife, bird life, fauna &

flora and a rich geological history. This area is mountainous and picturesque with

minimal light pollution.

Attending the ASSA weekend (from left to right): Sue & Alec Jemieson, Tony De Franca, Trevor Gould,

Tracey Benadie, Lee Herbst, Gary Els and Melvyn Hannibal.

page 14

Observing conditions were

considered ideal, clear and

although bitterly cold on the first

night, it proved to be one of the

finest night skies seen in a long

time. Those who attended were

mostly from the Joburg Centre

and needless to say they were a

friendly and helpful bunch of

amateur astronomers to say the

least. Four telescopes were set

up including the enormous and

impressive Meade LX200 12 inch

Schmidt Cassegrain telescope.

Above: although bitterly cold on the first night, observing conditions were considered ideal


Alec Jamieson and Melvyn Hannibal did the duty of erecting

the magnificent telescope on to its large tripod. Gary Els,

Chairman of the Johannesburg Centre also attended the

event. His enthusiasm for astro-photography brought some

more interest to the evening’s business. Spectacular photos

were taken of NGC 5139 or Omega Centauri, M17 or “Swan

nebula”, NGC 2070 commonly known as the “Tarantula

nebula” in the Large Megellanic Cloud (LMC), NGC 4755 or

“Jewel box” in Crux, only to mention a few of these gems.

Gary and Antonio photographed the Milky Way without the

aid of a telescope. These images were equally impressive: by

using a standard 18-55mm lens, wide aperture, high ISO

setting (3200 to 6400) and 5 to 40 second exposures produced

stunning results of the “heavens above”.

canopus july 2011

Above: Alec Jamieson setting up the 12” Meade

Portrait of The Milky Way: Nikon D60 camera, 18-55mm lens, 30 sec exposure

Further observations included Saturn, M4 globular cluster in Scorpius, NGC 5822 open

cluster in the constellation of Lupus the Wolf, M44 “Beehive open cluster” in Cancer and

a few more.

Saturday morning was welcomed by a proposal to visit a geological site in an

abandoned granite quarry near Venterskroon.

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Trevor expertly explained

how granite rock was

impacted by the

meteorite to form a black

crystallised molten rock

called “pseudotachylite”.

This rock was caused by

high impact pressure on

the existing granite and it

took millions of years to

cool down to its current

state.

Right: Trevor Gould describing

the geology after the meteorite

impact 2000 million years ago

The Vredefort Dome was a result of a meteorite impact. This occurred approximately

2000 million years ago and the damage caused when the meteorite collided in this

region was massive. The size of the meteorite was about 10km wide. The speed of this

meteorite was so fast that it exploded when it hit the ground. It blasted a mammoth

crater. This meteorite made a crater of about 300km in diameter and approximately

5km deep. This is the largest and oldest meteorite impact known according to

geologists.

In conclusion the outing was entertaining and fun with plenty jokes and laughter despite

the low turnout. A special thanks to the members of the Johannesburg Centre who

hosted the event, it was certainly a prelude to the next exciting astronomy event.

SA Astronomers Find Evidence for Planetary System

Submitted by Sharon Tait

http://www.saao.ac.za/no_cache/public-info/news/news/article/199/

page 16

Astronomers in South Africa find evidence for a strange new

planetary system

14 June 2011: Drs. Stephen Potter and Encarni Romero-Colmenero from the South

African Astronomical Observatory (SAAO) and collaborators have found evidence

for the existence of an extraordinary planetary system where two giant planets are

orbiting a close pair of “suns”.

If confirmed, this will be an example of a very strange planetary system, given the nature

of the stellar pair. The two stars, referred to as a white dwarf and a red dwarf, are each

smaller than our Sun and are so close that they take only a couple of hours to orbit each

other. The pair of them would actually fit comfortably within our Sun! By chance, the

system is oriented in such a way that the stars appear to eclipse each other once every

orbit as viewed from Earth. Dr. Potter and his collaborators noticed that the eclipses were


canopus july 2011

not occurring on time, but were sometimes too early or too late. This led them to

hypothesize the presence of two giant planets whose gravitational effect would cause

the stars' orbit to wobble and consequently slightly alter the measured time between

eclipses. The astronomers were also able to infer that the masses of the two planets must

be at least 6 and 8 times that of Jupiter and take 16 and 5 years respectively to orbit the

two stars. The system is too far away from us to be imaged directly.

Artist impression (Credit: http://www.saao.ac.za/typo3temp/pics/9f2c961304.jpg)

This binary star system (known as UZ For) would be an extremely inhospitable

environment. Due to their close proximity, the gravity of the white dwarf is constantly

“stealing” material from the surface of the red dwarf in a continuous stream. This

stream crashes onto the white dwarf where it gets super-heated to millions of

degrees and subsequently floods the entire planetary system with enormous

amounts of deadly X-rays.

This discovery was made possible by new SAAO and Southern African Large

Telescope (SALT) observations combined with archival data spanning 27 years,

gathered from multiple observatories and satellites.

A Big Surprise from the Edge of the Solar System

Submitted by Lerika Cross

June 9, 2011: NASA's Voyager probes are truly going where no one has gone before.

Gliding silently toward the stars, 9 billion miles from Earth, they are beaming back news

from the most distant, unexplored reaches of the solar system.

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Mission scientists say the probes have just sent back some very big news in deed. It's

bubbly out there.

page 18

Old view (Credit: http://science.nasa.gov/media/medialibrary/2011/06/09/oldview.jpg)

New view (Credit: http://science.nasa.gov/media/medialibrary/2011/06/09/newview.jpg)

Old and new views of the heliosheath. Red and blue spirals are the gracefully curving magnetic

field lines of orthodox models. New data from Voyager add a magnetic froth to the mix.


canopus july 2011

“The Voyager probes appear to have entered a strange realm of frothy magnetic

bubbles,” says astronomer Merav Opher of Boston University. “This is very surprising.”

According to computer models, the bubbles are large, about 100 million miles wide, so it

would take the speedy probes weeks to cross just one of them. Voyager 1 entered the

“foam-zone” around 2007, and Voyager 2 followed about a year later. At first

researchers didn't understand what the Voyagers were sensing—but now they have a

good idea.

“The sun’s magnetic field extends all the way to the edge of the solar system,” explains

Opher. “Because the sun spins, its magnetic field becomes twisted and wrinkled, a bit

like a ballerina’s skirt. Far, far away from the sun, where the Voyagers are now, the folds

of the skirt bunch up.”

When a magnetic field gets severely folded like this, interesting things can happen. Lines

of magnetic force criss-cross and “reconnect”. (Magnetic reconnection is the same

energetic process underlying solar flares.) The crowded folds of the skirt reorganize

themselves, sometimes explosively, into foamy magnetic bubbles.

“We never expected to find such a foam at the edge of the solar system, but there it is!”

says Opher’s colleague, University of Maryland physicist Jim Drake.

Theories dating back to the 1950s had predicted a very different scenario: The distant

magnetic field of the sun was supposed to curve around in relatively graceful arcs,

eventually folding back to rejoin the sun. The actual bubbles appear to be selfcontained

and substantially disconnected from the broader solar magnetic field.

Energetic particle sensor readings suggest that the Voyagers are occasionally dipping in

and out of the foam—so there might be regions where the old ideas still hold. But there is

no question that old models alone cannot explain what the Voyagers have found.

Says Drake: “We are still trying to wrap our minds around the implications of these

findings.”

The structure of the sun’s distant magnetic field—foam vs. no-foam—is of acute scientific

importance because it defines how we interact with the rest of the galaxy. Researchers

call the region where the Voyagers are now “the heliosheath.” It is essentially the border

crossing between the Solar System and the rest of the Milky Way. Lots of things try to get

across—interstellar clouds, knots of galactic magnetism, cosmic rays and so on. Will these

intruders encounter a riot of bubbly magnetism (the new view) or graceful lines of

magnetic force leading back to the sun (the old view)?

The case of cosmic rays is illustrative. Galactic cosmic rays are subatomic particles

accelerated to near-light speed by distant black holes and supernova explosions. When

these microscopic cannonballs try to enter the solar system, they have to fight through

the sun’s magnetic field to reach the inner planets.

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canopus july 2011

“The magnetic bubbles could be our first line of defense against cosmic rays,” points out

Opher. “We haven’t figured out yet if this is a good thing or not.”

On one hand, the bubbles would seem to be a very porous shield, allowing many

cosmic rays through the gaps. On the other hand, cosmic rays could get trapped inside

the bubbles, which would make the froth a very good shield indeed.

“We’ll probably discover which is correct as the Voyagers proceed deeper into the

froth and learn more about its organization1,” says Opher. “This is just the beginning,

and I predict more surprises ahead.”

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Credit: www.lab-initio.com/thumbnail/nz058B.jpg


Sharon’s APOM

Sharon Tait shares with us her favourite Astronomy Picture of the Month.

canopus july 2011

Photo credit: http://www.nasa.gov/multimedia/imagegallery/image_feature_1914.html

The View from Up Top

A low pressure system in the eastern North Pacific Ocean is featured in this image

photographed on Mar. 20, 2011 by an Expedition 27 crew member in the Cupola of

the International Space Station. Just under ten feet in diameter, the Cupola

accommodates two crew members and portable workstations that can control

station and robotic activities. The multi-directional view allows the crew to monitor

spacewalks and docking operations, as well as provide a spectacular view of Earth

and other celestial objects as evidenced in this image.

--0-0-0--

Credit: www.lab-initio.com/thumbnail/nz398.jpg

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canopus july 2011

The Sky this Month

Data provided by Brian Fraser

Site location: lat. 26.0 deg S long. 28.0 deg E local time – UT = +2.0 hrs.

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Local time of Rise and Set

Date Sun Mercury Venus Mars Jupiter Saturn Uranus

Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set Rise Set

Jul 5 6 57 17 30 8 28 19 8 6 9 16 37 4 34 15 8 1 54 13 11 11 56 0 11 23 34 11 37

Jul 10 6 57 17 32 8 32 19 24 6 16 16 44 4 30 15 2 1 38 12 54 11 37 23 52 23 15 11 17

Jul 15 6 56 17 34 8 31 19 35 6 23 16 51 4 27 14 56 1 21 12 36 11 17 23 33 22 55 10 57

Jul 20 6 55 17 37 8 26 19 40 6 28 16 59 4 23 14 51 1 4 12 19 10 58 23 15 22 35 10 37

Jul 25 6 52 17 39 8 16 19 40 6 33 17 8 4 18 14 45 0 47 12 1 10 39 22 57 22 15 10 18

Jul 30 6 50 17 42 8 0 19 33 6 37 17 17 4 14 14 40 0 30 11 43 10 21 22 38 21 55 9 58

Aug 4 6 47 17 44 7 39 19 16 6 39 17 26 4 9 14 35 0 12 11 25 10 2 22 20 21 35 9 38

Aug 9 6 43 17 47 7 13 18 51 6 41 17 35 4 4 14 29 23 54 11 6 9 43 22 2 21 14 9 17

Aug 14 6 39 17 49 6 42 18 16 6 42 17 44 3 58 14 24 23 36 10 47 9 25 21 44 20 54 8 57

Aug 19 6 35 17 51 6 11 17 37 6 43 17 53 3 53 14 19 23 17 10 28 9 6 21 27 20 34 8 37

Aug 24 6 30 17 54 5 45 17 3 6 42 18 1 3 46 14 14 22 58 10 9 8 48 21 9 20 13 8 17

Aug 29 6 25 17 56 5 30 16 41 6 41 18 10 3 40 14 9 22 38 9 50 8 30 20 52 19 53 7 57

Diary of Astronomical Phenomena 2011

July

d h d h

1 8 NEW MOON Eclipse 15 6 FULL MOON

2 23 Mercury 4.9N of Moon 18 6 Neptune 5.3S of Moon

4 18 Earth at aphelion 20 2 Mercury greatest elong E(27)

5 1 Regulus 5.3N of Moon 21 1 Uranus 5.8S of Moon

5 3 Mars 5.4N of Aldebaran 21 22 Moon at apogee

7 13 Moon at perigee 23 5 LAST QUARTER

8 6 FIRST QUARTER 23 21 Jupiter 4.9S of Moon

8 20 Spica 2.4N of Moon 27 2 Moon furthest North (23.3)

10 8 Uranus stationary 27 16 Mars 0.5N of Moon Occn

12 2 Antares 3.4S of Moon 28 23 Mercury 3.1S of Regulus

12 17 Moon furthest South (-23.4) 30 9 Venus 4.1N of Moon

14 0 Pluto 3.3N of Moon 30 18 NEW MOON

August

d h d h

1 8 Regulus 5.2N of Moon 17 8 Uranus 5.7S of Moon

1 10 Mercury 1.3N of Moon 18 15 Moon at apogee

2 6 Mercury stationary 20 9 Jupiter 4.7S of Moon

2 21 Moon at perigee 21 21 LAST QUARTER

5 1 Spica 2.3N of Moon 21 22 Venus 0.9N of Regulus

6 11 FIRST QUARTER 22 23 Neptune at opposition

8 4 Mercury 5.0S of Regulus 23 11 Moon furthest North (23.1)

8 8 Antares 3.5S of Moon 25 12 Mars 2.7N of Moon

8 23 Moon furthest South (-23.2) 26 1 Mercury stationary

10 6 Pluto 3.2N of Moon 28 0 Mercury 2.4N of Moon

13 19 FULL MOON 28 18 Regulus 5.1N of Moon

14 12 Neptune 5.2S of Moon 29 3 NEW MOON

16 12 Venus superior conjunction 30 17 Jupiter stationary

16 23 Mercury 5.9S of Venus 30 18 Moon at perigee

17 1 Mercury inferior conjunction


canopus july 2011

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canopus july 2011

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