is that the moon formed during a giant impact between the proto-Earth, and another protoplanet roughly the size of Mars, sometimes called “Theia.” In this theory, the moon formed from the impact ...

The moon is thought to be the aftermath of a ... involving a Mars-sized 'Theia' and proto-Earth. In this image, the proposed hit-and-run collision is simulated in 3D, shown about an hour after ...