Recently, there has been an … interesting idea for how we can form the moon. It answers all the geochemical questions: why is the moon so similar to the Earth? At least in the abundances of most of the elements, neglecting iron, nickel, and a few other elements.
Why don’t we put a giant atomic bomb at the core/mantle boundary? If it is big enough, we can blow off a portion of the crust and mantle lying above the bomb. This explains why the crust of the moon is like Earth’s crust/mantle and the tiny iron core of the moon.
This atomic bomb could be entirely natural. We find natural “geo-reactors,” or sites with naturally occurring regulated nuclear fission. We simply need a concentration of fissionable material such as uranium or thorium. In current nuclear reactors, we need enriched uranium in order to reach the critical mass necessary for a sustained fission reaction. But in large enough quantities (note: HUGE quantities) even un-enriched uranium can go critical.
This idea is that a giant collection of fissionable material collected at a spot on the core-mantle boundary and went SUPERcritical and caused a literal nuclear explosion. It would need enough energy to blast through the core and expel material off the surface of the Earth into orbit. Note: this idea isn’t expected to be the true mechanism of the formation of the moon, but we can’t yet disproven it, either. I’ll try to find the source later.