Tides Enlarge Moon Orbit Friction with the ocean beds drags the tidal bulges eastward out of a direct Earth-Moon line and since these bulges contain a lot of mass, their gravity pulls the moon forward in its orbit. The increase in speed enlarges the Moon's orbit. Currently, the Moon's distance from the Earth is increasing by about 3 centimeters per year. Astronomers have been able to measure this slow spiralling out of the Moon by bouncing laser beams off reflectors left by the Apollo astronauts on the lunar surface. The consequence of the Moon's recession from the Earth because of the slowing down of the Earth's rotation is also an example of the conservation of angular momentum . Angular momentum is the amount of spin motion an object or group of objects has. It depends on the geometric size of the object or group of objects, how fast the object (or group of objects) is moving, and the mass of the object (or the group). Since the Earth's angular momentum is decreasing, the Moon's angular momentum must increase to keep the
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