This artist's rendering provided by NASA on Thursday, April 17, 2014 shows an Earth-sized planet dubbed Kepler-186f orbiting a star 500 light-years from Earth. Astronomers say the planet may hold ... more 
This artist's rendering provided by NASA on Thursday, April 17, 2014 shows an Earth-sized planet dubbed Kepler-186f orbiting a star 500 light-years from Earth. Astronomers say the planet may hold water on its surface and is the best candidate yet of a habitable planet in the ongoing search for an Earth twin. (AP Photo/NASA Ames, SETI Institute, JPL-Caltech, T. Pyle) less 
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Associated Press | Photo By NASA Ames, SETI Institute, JPL-Caltech, T. Pyle
Thu, Apr 17, 2014 3:57 PM EDT