Kepler Spacecraft Discovers The First Rocky Planet

NASA's Kepler spacecraft has discovered Kepler-10b, its first confirmed rocky planet and the smallest transiting exoplanet discovered to date. Kepler-10b is only 1.4 times the size of Earth and has an average density of 8.8 grams per cubic centimeter, similar to that of an iron dumbbell. The planet orbits its star in only 0.84 days and is not in the habitable zone, where liquid water could exist.