Tuesday, April 24, 2007

Astronomers may have found E.T.'s home world

From what astronomers can tell, 581 c is a nice little planet, probably around half again as big around as Earth, a bit more gravity, temperatures amenable to liquid water and in fact not so different from the midwest (between freezing and 104 Fahrenheit). The orbital period is 13 days, so you get birthday cake every two weeks. Most important, it is there. For the first time, we found a planet outside our own solar system that fits our assumptions of what conditions are amenable to producing and supporting life.

581 c is the first extrasolar planet humans have found that falls into the range of being "hospitable to life"--a category which also contains Mars, so don't pack the space bikini yet. It is around Gliese 581, a dim star 20.5 light years away, in the constellation Libra. At Warp 1, that gives you a couple of decades to get into swimsuit shape, not counting the time it takes to develop warp drive.

As with so many scientific discoveries that sneak up on us, the first potentially habitable planet was not where we were looking for it. Gliese 581 is smaller, dimmer and cooler than the sun, and while plenty of extrasolar planets have been found around stars like Gliese 581--including one the size of Neptune around Gliese 581--planet hunters looking for earthlike planets tended to concentrate their efforts around stars like our sun. In the project that discovered 581 c, about 90% of the telescope time went to sun-like stars. The new planet was found in the other 10%. Makes me wonder what else we have been missing because we assume it can't be there.

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