Artist's concept of Kepler-186f, the first Earth-size planet found orbiting in the habitable zone of its parent star. Kepler-186f orbits a red dwarf about 490 light-years from Earth. (NASA Ames/SETI Institute/JPL-Caltech)
This past year was a banner one for the field of exoplanet science, with the tally of known alien worlds doubling to nearly 2,000 by the end of 2014.
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