Kepler exoplanets and Earth. Illustration comparing Earth (far right) with five Earth-like exoplanets discovered by NASA's Kepler space observatory. This spacecraft was launched in 2009 and has discovered over 1000 planets so far. The exoplanets shown here are habitable-zone planets with similarities to Earth. From left: Kepler-22b, Kepler-69c, Kepler-452b, Kepler-62f and Kepler-186f. The discovery of Kepler-452b was announced on 23 July 2015, and it is thought to be the most Earth-like planet discovered to date, close in size and with a star very similar to that of our Sun. The other exoplanets shown here are either larger or have smaller parent stars.