Enlarge Known for the time being as Gliese 581c, this is the first planet we have found that can actually support life. It is 20.5 light years away, and has the right temperature to allow liquid water on its surface. The average surface temperature is estimated to be between zero and 40c (32-102f). Lakes, rivers and even oceans are possible. It has a mass five times that of Earth, probably made of the same sort of rock that makes up our world and with enough gravity (around twice that of earth) to hold a substantial atmosphere. This remarkable discovery appears to confirm the suspicions of most astronomers that the universe is swarming with Earth-like worlds.
