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On 17 April 2014 , the discovery of the Earth-size exoplanet Kepler-186 f , 500 light-years from Earth , was publicly announced ; it is the first Earth-size planet to be discovered in the habitable zone and it has been hypothesized that there may be liquid water on its surface .
 Kepler-186 f, Earth
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 Kepler-186 f, Earth