Will We Discover "Earth's Twin" This Year?

NASA's Kepler Space Telescope has found more than 2,300 potential planets since its March 2009 launch. Although astronomers have found a number of exoplanets that share one or two key traits with our planet, including size or inferred surface temperature, a true "alien Earth" has yet to be discovered. Scientists have claimed that Earth's twin will be discovered at some point in 2013.