Kepler 22b

Kepler 22b

This is an artist rendering of Kepler 22b, which lies 600 light years away from Earth in the constellation of Cygnus. It's the first planet we've found that's located right smack in the middle of the habitable zone around its star (sun), making it an earth-twin in the right spot for sustaining possible life. Discovered by the Kepler space mission, this planet is the first world smaller than Neptune to be found in middle of its star's habitable zone.

Also called the Goldilocks zone, the habitable zone is the region around a star where a planet's surface is not too hot and not too cold for liquid water—and thus life as we know it—to exist. In fact, only two known planets fit this description so far—Gliese 581d and HD 85512—and both worlds orbit at the very edges of their stars' habitable zones, making them more akin to Venus and Mars than to Earth. It's also orbiting a star that's almost a twin of our sun, whereas the other two detections are orbiting significantly cooler stars.

Kepler 22b is about 2.4 times the radius of Earth, but scientists don't yet know its composition, because they are still missing a crucial piece of information: Kepler 22b's mass.

However, no information is available about the shape of the planet's orbit. Many extrasolar planets are known to move in highly elliptical orbits. We only know that the semi-major axis of its orbit is within its host star's habitable zone. If Kepler-22b has a highly elongated orbit it may well only spend a small fraction of its time within this habitable zone, which would cause extreme temperature differences on the planet and make it inhospitable.

It's exciting to think there could be life on another planet, I for one am waiting eagerly to see what new things we can learn about Kepler 22b.