Phobos- Doomed Moon

Mars' two moons, Phobos and Deimos, are named for minor Greek gods of Fear and Panic. Phobos, the larger and cloeser of the two, is spiraling inwards toward Mars' surface, and it will be destroyed entirely in about a hundred million years. It will either crash to the surface or, more likely, break up while in orbit and form a planetary ring. Compared to our moon, 400,000 km above the planetary surface, Phobos is only about 5,000 km away from Mars, and orbits so fast that it appears to rise in the West and set in the East.