On 5 December 2011, NASA’s Kepler mission confirmed the discovery of the planet Kepler-22b which was spied by NASA’s Kepler space telescope.

It is considered to be an Earth-like planet. It is the first planet in the habitable zone i.e. the region where liquid water exists on the planet. It is the smallest extrasolar planet orbiting in the middle of the habitable zone of a G-type star which is similar to the sun, Kepler-22. It’s not confirmed whether the planet is solid or gaseous.

Kepler-22b is located 600 light-years away from Earth. It lies in the constellation of Cygnus. It is larger than the Earth and it orbits 290 days around its sun-like star. Its radius is about 2.5 times the radius of Earth. It could be mostly ocean with a small rocky core. The astronomers noted its temperature to be the same as that of Earth. The greenhouse effect is the same, then the scientists estimates it’s temperature to be slightly warmer than Earth i.e. 22 degrees Celsius or 72 degrees Fahrenheit which are life-friendly. The density, mass and surface gravity is not known, but it is greater than that on Earth.