Mars’ moons Phobos and Deimos potentially result of a collision with a body a third the planet's size, rather than captured asteroids, new Nature study finds. The impact would have produced many moons, most of which have since fallen from orbit.

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Mars’ moons Phobos and Deimos potentially result of a collision with a body a third the planet's size, rather than captured asteroids, new Nature study finds. The impact would have produced many moons, most of which have since fallen from orbit.