Nature Photographs (c) Andreas Stridsberq

Conditions on the other terrestrial planets, Mercury and Venus, appear to be too harsh to support life as we know it. But it has been conjectured that Europa, the fourth-largest moon of Jupiter, may possess a sub-surface ocean of liquid water and could potentially host life.
Recently, the team of Stéphane Udry have discovered a new planet named Gliese 581 g, which is an extrasolar planet orbiting the red dwarf star Gliese 581. Gliese 581 g appears to lie in the habitable zone of space surrounding the star, and therefore could possibly host life as we know it.