Kepler-10b, the first undeniably rocky planet,[5] was discovered in its orbit after eight months of observation and announced on January 10, 2011. The planet orbits its star closely, completing an orbit every 0.8 days,[6] and has a density similar to that of iron.[5] The second planet, Kepler-10c, was confirmed on May 23, 2011, based on follow-up observations by the Spitzer Space Telescope. The data shows it has an orbital period of 42.3 days and has a radius more than double that of Earth, but a higher density, making it the largest and most massive rocky planet discovered as of June 2014.[2][7][8]