What is the origin of our moon?
There have been a number of different theories as to how the Moon formed. However, one of these theories has risen to be the most widely accepted because of discoveries made using the rocks that were brought back from the Moon by the Apollo missions. Trashcity covers the problems with two of these theories pretty well, except for the one that has the Moon forming in a different part of the solar nebula. The problem with that theory is that, if the Moon formed at a different location in the solar system, then it would have a different isotopic composition than Earth. This is not the case. The Moon’s isotopic composition is the same as Earth’s. Therefore, it formed in our neighborhood. Currently, the most popular model for the Moon’s formation is the Giant Impact Model. This model state that as Earth was nearing the end of it’s formative period, another planet about the size of Mars crashed into it. This theory explains the observed facts pretty well. When this other planet slammed into
