Just two weeks after the confirmation of a planet that’s within the habitable zone of a distant star, the Kepler team is back with the discovery of two Earth-sized planets orbiting in what is now a five-planet system (three other planets orbiting the star, Kepler-20, had been spotted earlier). Although these planets are much too hot to support liquid water, one of them (Kepler-20e) is the smallest exoplanet yet detected.
Kepler-20 was already a busy star system, with three small planets orbiting close in to the star: Kepler-20b is about twice the size of Earth and orbits once every 3.7 days; Kepler-20c is three times Earth’s radius and orbits every 11 days; and Kepler-20d is 2.75 Earth radii with an orbit of 77.6 days. If that seems somewhat tightly packed, the new finds actually jam a couple more planets within the orbit of Kepler-20d. Kepler-20e has an orbit of six days, while Kepler-20f takes 19.6 days to orbit its host star.
Kepler team spots Earth-sized planets orbiting sun-like star