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Amateur astronomy
Running rings around a distant planet
Feb 17th 2005
From The Economist print edition
Astronomers may have found their first Saturn lookalike
LAST summer, millions of people around the world watched the silhouette of Venus slide across the face of the sun—the first such “transit” for 122 years. At about the same time, a team of professional astronomers was pulling off a similar trick for a planet the size of Jupiter in orbit around a star 32m times farther from Earth than the sun. It was the first triumph for the Trans-Atlantic Exoplanet Survey (TrES), a set of three tiny telescopes, one on Tenerife and the other two in Arizona and California. Each telescope has a mirror just 10cm across, yet working together they detected the microscopic dimming caused by a planet getting in the way of the distant star.
Having announced the existence of TrES-1b, as the planet is now known, the TrES team stopped watching and moved on to search for others. In so doing, it may have missed the greatest surprise of all. For TrES-1b appears to be surrounded by a massive ring system, like Saturn's but bigger. And this discovery was made not by professionals, but by a network of amateur astronomers spread throughout the world, using back-garden telescopes and swapping their data via the internet.
Transitsearch.org, as the amateur network is known, was actually dreamed up by a professional. It is the brainchild of Greg Laughlin of the University of California, Santa Cruz. He realised that some of the off-the-shelf equipment used by serious amateurs is sensitive enough to measure the light drop caused by distant transits. His irregulars soon went to work on the newly discovered TrES-1b, and when they pooled their results they found that there was a peculiar rippling pattern of brightening and dimming lasting about 40 minutes at the beginning and the end of each transit. This rippling suggested a series of rings crossing in front of the star in advance of, and then behind, the profile of the transiting planet.
Not everyone is convinced—if only because the rings would have to be much denser than those of Saturn in order to explain the observation. But it is enough for Timothy Brown, the leader of the TrES team, to have booked time on the Hubble space telescope to have a better look. And if he sees rings too, then it will be a feather in the cap of amateur science.
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