GJ 1214b
GJ 1214b GJ 1214b is a "super-Earth" orbiting a small star located 40 light-years from our solar system. Observations suggest that its density is lower than that of Earth, so that it probably has a Ganymede-like composition (a metal and rock core overlain by a thick mantle of water in liquid or ice form). Unlike Ganymede, GJ 1214b is probably covered with a thick atmosphere of hydrogen and helium. ESO / L. Calcada