Untitled - the ultimate blog

More documents

Recommendations

Info

Detecting habitable new worlds The next blue planet Aug 13th 2009 | RIO DE JANEIRO From The Economist print edition The race is on to discover a second Earth IN 1995, when Michel Mayor of the University of Geneva detected the first exoplanet (a planet that orbits a star other than the sun) he started a race that has gained pace ever since. Some 360 such planets have now been detected, but none is exactly equivalent to the Earth. The closest so far is Gliese 581c, which was discovered in 2007 by Dr Mayor’s colleague, Stéphane Udry. It is both rocky and orbits its parent star at a distance where liquid water could reasonably be expected to exist. However, since its parent star is a red dwarf—a far smaller and fainter object than the sun—that orbit is, in fact, much smaller that the Earth’s around the sun. That, in turn, suggests Gliese 581c is likely to be tidally locked to its orbital period, so that one side of the planet always faces the star and the other never does. Having half a planet in permanent daylight and the other half in permanent darkness does not sound like a good recipe for life. As astronomers heard this week at the International Astronomical Union meeting in Rio, two new missions—a French one launched in December 2006 and an American one launched on March 6th—are in the process of trying to add to the list. Dr Mayor told the meeting that the French mission, CoRoT, has now found 80 exoplanets. It does so by watching for small diminutions in the amount of light from a star as the planet in question passes in front of it, a phenomenon known technically as a transit. The details of all but seven of these transiting planets are still unpublished, but Dr Mayor gave the meeting a preview. The planets discovered so far by CoRoT typically have a mass that is less than 30 times that of Earth, making them likely to have a solid, rocky surface. But they also orbit their stars rapidly, typically taking two or three months, rather than a year, to do so. For those who hanker after extraterrestrial life that is a pity. Such rapid orbits mean the planets in question are close to their parent stars, and thus likely to be tidally locked. Other news from CoRoT is better, though. Some 80% of the planets Dr Mayor has found have siblings. The existence of so many neighbours suggests that planetary systems tend to be stable, and stability is good for the evolution of life. Dr Mayor described a system he has seen that has five rocky planets in it. They have masses of 11, 14, 26, 27 and 76 times that of the Earth. He concluded his talk by saying, “I am really confident that we have an Earth-like planet coming in the next two years.” He and his team may, however, be pipped at the post. On August 6th America’s space agency, NASA, announced that its Kepler planet-detector (named after the man who worked out the laws of planetary motion, as this article explains) is also behaving well. A paper published in Science by William Borucki of the NASA Ames Research Centre based in Moffett Field, California, and his colleagues showed that Kepler, which also uses the transit-detection technique, has confirmed the existence of a Jupiter-like planet discovered in 2007 and provided more precise details of that planet’s mass and orbital period. And Kepler’s instruments are more sensitive than CoRoT’s, so it should be capable of finding Earth-sized planets more easily than its French cousin. Yet such space probes are not the only way of searching for other Earths. As part of his efforts to find new worlds, Dr Mayor is using the HARPS spectrograph, which is based at the European Southern Observatory in La Silla, Chile. He and his colleagues are training HARPS on ten nearby, bright and quiet stars three times a night, for 15 minutes at a time, for 50 nights a year, for at least two years, in the hope of spotting a nearby Earth-sized planet. The device works by detecting the tiny wobble given to a parent star when a planet passes it by. The spectrograph has already found 16 planets. Meanwhile, David Bennett of the University of Notre Dame in Indiana wants to use a technique called gravitational microlensing to spot planets that might be missed by other methods. He told the conference that his approach would pick up not only small rocky planets orbiting at great distances from their parent stars, but also planets that had been ejected from their orbits. The idea would be to stare at a distant star -123-
and report instances when its light had been bent by the gravity of a planet passing in front of it. Such signals would be brief and rare, but they would also be strong and unmistakable. Sooner or later, then, an Earth-sized planet will turn up. How Earth-like it will be in other ways, remains to be seen. Copyright © 2009 The Economist Newspaper and The Economist Group. All rights reserved. -124-
Page 2 and 3:
Search Requires subscription Econom
Page 4 and 5:
Politics this week Aug 13th 2009 Fr
Page 6 and 7:
Business this week Aug 13th 2009 Fr
Page 8 and 9:
KAL's cartoon Aug 13th 2009 From Th
Page 10 and 11:
Asia’s rebound has several causes
Page 12 and 13:
democratic region. But Brazil’s l
Page 14 and 15:
World trade and commercial aircraft
Page 16 and 17:
Galileo, four centuries on As impor
Page 18 and 19:
Correction: America's sex laws Aug
Page 20 and 21:
SIR - You mentioned the slaughter d
Page 22 and 23:
Professor of the history of art Sch
Page 24 and 25:
Their arrival coincides with, and i
Page 26 and 27:
and integrated well.) Peru has beco
Page 28 and 29:
Clean energy in the Midwest Greenin
Page 30 and 31:
The economics of natural gas Drowni
Page 32 and 33:
meetings on health reform planned f
Page 34 and 35:
Drought in Texas Not a cloud Aug 13
Page 36 and 37:
Rich animals The dog will have his
Page 38 and 39:
twice the national average. But it
Page 40 and 41:
international institutions and the
Page 42 and 43:
Energy v environment in Canada Bomb
Page 44 and 45:
further sanctions. Yet it is doubtf
Page 46 and 47:
egistered voters are frauds. Yet Mr
Page 48 and 49:
Australia's opposition His own wors
Page 50 and 51:
Taiwan's typhoon Taiwan's disastrou
Page 52 and 53:
Banyan The Burmese road to ruin Aug
Page 54 and 55:
Fatah and the Palestinians Fresh fa
Page 56 and 57:
Iran and human rights The crackdown
Page 58 and 59:
Security in Iraq A return to the ba
Page 60 and 61:
Ethiopia's resilient prime minister
Page 62 and 63:
America and Africa Hillary (not Bil
Page 64 and 65:
Southern Italy's ills The messy mez
Page 66 and 67:
Copyright © 2009 The Economist New
Page 68 and 69:
Italy's vigilantes On the beat Aug
Page 70 and 71:
crisis-driven entanglement in banks
Page 72 and 73:
colluded with the Russian patriarch
Page 74 and 75:
Prospects for recovery Mervyn's rea
Page 76 and 77: Conservatives will be fighting over
Page 78 and 79: advanced to scale down much. If the
Page 80 and 81: Scotland's capital and recession Pa
Page 82 and 83: Edinburgh festivals Fringe-onomics
Page 84 and 85: Bagehot Love in the time of swine f
Page 86 and 87: Correction: Teaching in Britain Aug
Page 88 and 89: Their aim is more modest. It was sp
Page 90 and 91: At a review conference next year, s
Page 92 and 93: All this would not matter much, wer
Page 94 and 95: with state aid. In an average year
Page 96 and 97: Mauro Cutrufo, Rome’s head of tou
Page 98 and 99: Online auctions Mind the pennies Au
Page 100 and 101: hire in anticipation; they will wai
Page 102 and 103: Face value Top of his game Aug 13th
Page 104 and 105: Emerging Asian economies On the reb
Page 106 and 107: y 70%. One reason why Asia’s emer
Page 108 and 109: industries with subsidies and under
Page 110 and 111: Of the three firms, AIG represents
Page 112 and 113: Assessing quantitative easing Muzzl
Page 114 and 115: All these rules failed and the sche
Page 116 and 117: Retail bonds in Europe Small fry wa
Page 118 and 119: A current-account surplus that has
Page 120 and 121: politicians still seem fixated by e
Page 122 and 123: In an influential early example of
Page 124 and 125: Thinking space Another way to encou
Page 128 and 129: The history of science Kepler's wor
Page 130 and 131: Engels (whose name resembles the wo
Page 132 and 133: prose, having gone from Uighur to G
Page 134 and 135: anks to hold more capital, the flow
Page 136 and 137: Football and economics Game for gee
Page 138 and 139: There are two intellectual bugbears
Page 140 and 141: she continued to lurk, roiling the
Page 142 and 143: Output, prices and jobs Aug 13th 20
Page 144 and 145: The Economist commodity-price index
Page 146 and 147: Trade, exchange rates, budget balan
Page 148 and 149: Markets Aug 13th 2009 From The Econ
Page 150: Office vacancy rates Aug 13th 2009
show all

Untitled - the ultimate blog

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?