This image compares the first Earth-size exoplanets found around a Sun-like star to planets in our own solar system, Earth and Venus. NASA's Kepler mission discovered the newfound planets, called Kepler-20e and Kepler-20f. Kepler-20e is slightly smaller than Venus with a radius .87 times that of Earth. Kepler-20f is a bit larger than Earth at 1.03 times the radius of Earth. The paper presenting the discovery was led by Francois Fressin of Harvard University.