spacetoday.net: Earth-like exoplanet discovered

Posted: Wed, Apr 25, 2007, 8:27 AM ET (1227 GMT)
Gliese 581c Earth-like exoplanet (ESO)

Astronomers announced late Tuesday that they have discovered a planet orbiting another star that is the closest yet to the Earth, including an orbit that would give the extrasolar planet Earth-like conditions. The planet, Gliese 581 c, orbits a red dwarf 20.5 light-years away from the Earth. The planet has a radius 50 percent larger than the Earth's and a mass about five times as great, making it one of the smallest exoplanets yet discovered and also likely to have a rocky or water-covered surface. The planet's orbit would give it surface temperature of between 0 and 40 degrees Celsius, making it the most habitable of any exoplanet yet found. Astronomers had previously discovered a larger planet, roughly the size of Neptune, orbiting the star, and a third planet with a mass between the two known exoplanets may also exist. European astronomers made the discovery using a very sensitive spectrograph on a telescope at the European Southern Observatory in Chile; the spectrograph was able to detect the feeble tugs on the star caused by the orbiting planets.