Various: The European Southern observatory last night announced the discovery of a planet only 50 percent larger than the Earth, and a mass five times as great, in orbit around Gliese 581, a nearby star 20.5 light years away. The planet, called Gliese 581c, orbits in the temperate zone, the region in which water can be liquid, thus making Gliese 581c the first planet outside our solar system that could be habitable.

However, astronomer Wesley Traub of NASA's Jet Propulsion Laboratory in Pasadena, Calif, tells USA Today that he doubts Gliese 581c is hospitable enough for life. "It is probably tidally locked to the star, like the moon to the Earth," he says. That means the star-facing side of the planet receives boiling heat, while the far side would be frozen.

The discovery was made by 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. A paper about Gliese 581c has been submitted to Astronomy & Astrophysics, but the results have not yet been confirmed independently.