Gliese 581 d is a planet that is believed to be able to support life, 20 light years away.
It is at the right distance away from its star (sun). It is in the HABITABLE ZONE where water could exist. With water, life is possible.
But it much bigger than earth though, and astronomers termed it a "Super Earth".
The planet was discovered by astronomers in 2007, on the constellation of Libra. Gliese 581 d orbits around the star Gliese 581, a red dwarf star in the constellation Libra.
"In astronomical terms it is one of our near neighbors, the 87th closest known star system to the sun," said Carole Haswell, an astronomer at the Open University in Milton Keynes, U.K.
source - National Geographic and Wikipedia
I guess the possibility of life out there is quite high. There are billions of stars in our own galaxy, and even MORE planets orbiting these stars.
Tell me the probability rates. :)