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Astronomers Find Three Smallest Planets Outside Solar System

smallest alien planets
(Image credit: NASA/ JPL-Caltech)

Astronomers have discovered the three smallest alien planets yet, including one that's just the size of Mars.The alien worlds, detected using publicly available data from NASA's Kepler mission, are 0.78, 0.73 and 0.57 times the diameter of Earth, respectively; the smallest one is roughly Mars-size.

Space.com Staff
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