Mars has two small moons, Phobos and Deimos, whose names are Greek for Fear and Panic. These moons may even be captured asteroids that originated from the main asteroid belt between Mars and Jupiter. The larger moon Phobos (pictured) is seen to be cratered in this picture from the Mars Reconnaissance Orbiter. Phobos orbits so close to Mars that gravitational tidal forces are dragging it down. In about 100 million years Phobos will likely be shattered by stress caused by tidal forces, with its debris forming a decaying ring around Mars.