Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Mars has two tiny moons, Phobos and Deimos . Pictured above is Deimos , the smaller moon of Mars . In fact, Deimos is one of the smallest known moons in the Solar System measuring only 9 miles across. Washington D.C. The existence of two Martian moons was predicted around 1610 by Johannes Kepler , the astronomer who derived the laws of planetary motion.
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