The Origins of the Moon

In the early moon we think was much, much closer to the Earth. And then over time it spirals out and ends up becoming tidally locked to theEarth. One reason we think this is that we've been to the moon and we've been able to study what it's made out of. The moon has fewer of like volatile elements. Things that vaporize at low temperatures were probably lost in this high energy event. So the Earth and the moon don't have exactly the same kinds of stuff.