Scientists Identify 20 Alien Worlds Most Likely to Be Like Earth

An international team of researchers has identified the 20 most Earth-like worlds among the more than 4,000 exoplanet candidates that NASA's Kepler space telescope has detected to date, scientists report in a new study. All 20 potential "second Earths" lie within the habitable zones of their sun-like stars — meaning they should be able to harbor liquid water on their surfaces — and are likely rocky, the researchers said. Identifying these Earth-like planets is important in the hunt f