Discovered: The First Earth-Sized Worlds Outside Our Solar System
Kepler-20e Kepler-20e orbits its star every 6.1 days. At just 4.7 million miles from its star, its surface temperature reaches a searing 1,400 degrees F. NASA/JPL-Caltech/T. PyleThe smallest exoplanets yet Two small, scorched Earth-sized worlds orbiting a reddish sun-like star in the Cygnus constellation mark yet another milestone for the storied Kepler Space Telescope mission. They're the smallest exoplanets found to date - one of them is just 1.03 times the size of Earth, a veritable body double. The planets aren't in their star's habitable zone, but they are the right size - and as such, they fill in even more of the interstellar planetary puzzle. The planets exist in a strange configuration that sandwiches them among three gas giants, and they're all well within the orbit of Mercury. They were buried in nearly two years of data, and astronomers had to use some ultra-refined computational techniques to be sure...