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About "Martian Moon Mystery"

Astronomers have long puzzled over Mars' two diminutive moons, Phobos and Deimos. They appear to be little more than captured asteroids, but their orbital mechanics do not fit this hypothesis. Instead, one theory (among many) is that the two modern moons are fragments of a much larger moon existed billions of years ago. The idea is that this moon was roughly 15 times the mass of Phobos, sat between the current orbits of the modem two moons, and was strong enough cause water tides. It slowly spiralled in towards Mars — which had water at this time — until it became torn apart by tidal forces, as shown here. Later, debris from this event coalesced into Photos and, higher up, Deimos.