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Artist rendering of the Moon's formation

How Did the Moon Form?

Today, there are several main theories on the origin of the Moon. The most widely accepted of these theories states that the Moon formed after a Mars-sized protoplanet (a young planet not yet fully formed), collided with the early Earth over 4 billion years ago. This massive collision produced debris that eventually coalesced due to gravitational forces to form the Moon. Image Credit: William Hartmann, space artist