So how did our planet end up with such a special moon? The answer is that, surprisingly enough, the moon is a piece of our ...

According to a new theory, there were two giant impacts in a row, separated by about one million years, involving a Mars-sized 'Theia' and proto-Earth. In this image, the proposed hit-and-run ...

The giant-impact hypothesis posits that billions of years ago a Mars-sized body named Theia collided ... existed and if it collided with the young proto-Earth, but the evidence is compelling.