Kepler-22b

Kepler-22b (also known by its Kepler Object of Interest designation KOI-087.01) is an extrasolar planet orbiting within the empirical habitable zone of the Sun-like star Kepler-22. It is located about 600 light-years (180 pc) from Earth in the constellation of Cygnus. It was discovered by NASA's Kepler Space Telescope in December 2011 and was the first known transiting planet to orbit within the habitable zone of a Sun-like star.

Kepler-22b's radius is roughly twice that of Earth. The mass is below 52.8 Earth masses to 95% confidence. Its surface composition remains unknown - dubbed by scientists as a "waterwold " it might be an "ocean-like" planet ("mostly ocean with a small rocky core"). An Earth-like composition is unlikely.