Earth collided with another planet, Theia, creating the Moon

About 100 million years after the creation of our planet, a collision occurred between the Earth and a baby planet, Theia, The smaller planet disappeared inside the Earth, but fragments of the amalgam flew off into space, where they coagulated into a new body: the Moon.

A recent study carried out by researchers from the University of California in Los Angeles (UCLA) has revealed that the collision was strictly head-on, which explains why the chemical composition of Moon rocks is quite similar to that of Earth rocks. If Theia and Earth had collided obtusely, then much of the Moon would have been composed mainly of Theia, meaning that the chemical compositions of the Moon and the Earth would have been significantly different.