For years, scientists have been discovering exoplanets — planets orbiting stars other than our own. These planets are generally gas giants like Jupiter and Saturn and are not capable of supporting life as we know it. A recent discovery, however, proves the existence of relatively small, rocky worlds not unlike Earth.
The planet, named Kepler-10b, is a rocky world that is 1.4 times the size of Earth circling a star about 560 light-years away. It circles its star 20 times closer than Mercury and has a surface temperature of 2,500 degrees. Also, because of its proximity, it is incapable of holding an atmosphere because of the massive amounts of radiation to which it is exposed.
NASA's Kepler mission found this planet based on a small shift in light from its star — a sun-like orb about twice as old as ours. Because of the proximity of the planet to its sun, it orbits in approximately one day, which provided a vast amount of light shifting over the past eight months and made it fairly easy to find. A similar planet at Earth's distance from its sun would circle in a similar time frame as we do — 365 days — and is much more difficult to track and find.
Some have theorized that the planet may have originated much further away from the star and through some catastrophic event moved inward; others assume it formed where it currently orbits. Either way, if the planet supported life in the past, there's no way it could now.
For more details, watch this short video about Kepler-10b.