Question: how was the moon created

Graham Shields answered on 2 Feb 2021:

The Moon formed during the early solar system times. Back then, there were a lot more planetary bodies, both large and small, orbiting the Sun, with plenty of crashes between them. We think that one such collision occurred between a Mars-sized planet and the early Earth. The smash caused both planets to melt and a blob of magma escaped the Earth’s gravity, forming the Moon. That explains why Earth has a large metal core (because it kept the one it already had and gained some more), but the Moon only has a tiny one – otherwise, they are chemically very similar. Scientists have hypothesised this from the decay of short-lived radioactive isotopes.