But at least some solace comes from the Kepler space telescope team's estimate that just in our Milky Way galaxy alone, some 500 million planets likely orbit inside their star's habitable zone ...

Imagine the potential for life and unique environmental conditions if the exoplanet Kepler-22b were located within our solar system.

Kepler-22b is the first extra-solar planet, or exoplanet, that the Kepler Space Telescope found in the habitable zone of its star. It is thought to be a promising spot to search for life.

Imagine stepping onto a distant exoplanet, where vast alien oceans stretch beyond the horizon. Based on data from missions ...

The new planet - named Kepler-22b - has key aspects it shares with Earth. It circles a star that could be the twin of our sun and at just about the same distance.

A newly discovered planet is eerily similar to Earth and is sitting outside our solar system in what seems to be the ideal place for life, except for one hitch. It's a bit too big.

The exoplanet, given the undramatic name of Kepler 22b, was found by NASA's Kepler spacecraft as part of its mission to seek out Earth-type planets in our galaxy.

We are almost there." The new planet — named Kepler-22b — has key aspects it shares with Earth. It circles a star that could be the twin of our sun and at just about the same distance.

This illustrated graphic shows the two newfound Kepler-20 planets shown to scale with Earth and Venus. But is there any chance that life that doesn't require water could exist on Kepler-20e and 20f?

The Kepler Space Telescope has run out of fuel and ended its 9.5-year career, just days after astronomers announced possible evidence of a moon orbiting an exoplanet.

Previously, the smallest planet with known radius inside a habitable zone was Kepler-22b, with a radius of 2.4 times that of the Earth.