About this world
Kepler-22 b is a sub-Neptune orbiting Kepler-22, a yellow, Sun-like star (type G5V) 635 light-years from Earth. It is about 2.1 times the size of Earth and holds 9.1 Earth masses. It completes an orbit every 290 days at 0.81 AU from its star, on a strongly elongated orbit (e = 0.72).
Its equilibrium temperature is about 279 K (6 °C), which places it in the conservative habitable zone: the band where liquid water could exist on a rocky surface. By the "cosmic shoreline", it has likely held on to an atmosphere. Its atmosphere has already been studied: 2 spectroscopic observations.
It was discovered in 2011 by transit with Kepler. A planet crosses its star and dims it by a tiny, periodic fraction.