The planet Kepler-78B, the first known Earth-sized planet with an Earth-like density, is seen in an undated artist rendering released by the Harvard-Smithsonian Center for Astrophysics October 30, ... more 
The planet Kepler-78B, the first known Earth-sized planet with an Earth-like density, is seen in an undated artist rendering released by the Harvard-Smithsonian Center for Astrophysics October 30, 2013. Kepler-78B circles a star that is slightly smaller than the sun located in the constellation Cygnus, about 400 light years away. REUTERS/David A. Aguilar/Harvard-Smithsonian Center for Astrophysics/Handout (UNITED STATES - Tags: SCIENCE TECHNOLOGY) THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. IT IS DISTRIBUTED, EXACTLY AS RECEIVED BY REUTERS, AS A SERVICE TO CLIENTS. NO SALES. NO ARCHIVES. FOR EDITORIAL USE ONLY. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS less 
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Reuters | Photo By HANDOUT / Reuters
Wed, Oct 30, 2013 10:45 PM EDT