21 Science Facts You Won't Believe Are True

18. The Moon Was Formed By A Planet Crashing Into Earth

The Earth hasn't always had a moon, and many astrophysicists think that we could have gained our nocturnal companion as a result of a massive collision between the Earth and another large object during the early stages of the formation of the solar system.

It's not certain what this huge body was. Some scientists think that it could have been a planet the the size of Mars called Theia that all but vaporized both us and itself in the crash, and the debris then coalesced into our moon.

17. The Moon Is Moving Away From Us

Speaking of the moon, it used to be much closer to the Earth than it is today, and has been moving away from us at a rate of around 3.78 centimetres (1.48 inches) every year.

This is caused by the braking effect of the tidal bulge that is, in turn, caused by the moon's gravitational pull. It is thought, however, that the moon will never truly abandon us, as the tidal forces will get weaker, the further it wanders and it may eventually end up in a geostationary orbit around the Earth.