How did the moon form? The leading theory is that the Moon resulted from a glancing collision between the young Earth and an object the size of Mars. The above image series is based on several mathematical simulations of the Moon’s origin:
The Moon’s history begins with a collision between a young Earth (larger object) and a Mars-sized planet.
10 minutes: The now-molten mantle layers (gray) of the two planets are mixing together.
1 hour: The iron cores (orange) are melding together – Most of this iron will remain with Earth.
2 hours: Parts of the mantle are spinning off into a swarm of debris.
22 hours: Pieces of debris revolve around Earth, slowly gathering together.
1 week: The growing Moon’s gravity pulls in the remaining debris.