The moon Phobos has a mysterious origin but a certain expiration date. Phobos, one of Mars' moons, has an uncertain origin, but its surface grooves show that tidal forces are pulling it apart. In time ...

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For a small, lumpy chunk of rock that barely reflects any light, Mars’ Moon Phobos draws a lot of attention. Maybe because it’s one of only two moons to orbit the planet, and its origins are unclear.

Mars is the fourth planet from the sun and has a distinct rusty red appearance and two unusual moons. The Red Planet is a cold, desert world within our solar system. It has a very thin atmosphere, but ...