Evolution of the moon This video was produced by NASA in honor
of 1,000 days in orbit by the Lunar Reconnaissance Orbiter
(LRO). It takes viewers through the moon's evolutionary history,
and reveals how it came to appear the way it does today. The
moon did not always look this way. It likely started as a giant
ball of magma formed from the remains of a collision by a Mars-
sized object with the Earth about four and a half billion years
ago.