Coldest exoplanet

OGLE-2005-BLG-390Lb, discovered in 2006, orbits a cool red dwarf star 21,000 light years from Earth. The low energy of its star coupled with the size of its orbit (corresponding to between that of Mars and Jupiter around the Sun), means its surface temperature is just -220 C. Its mass is estimated at around five times that of Earth’s and it probably has an icy surface, rocky core and thin atmosphere.