I understand that the latest accepted theory for the formation of the Moon indicates that a Mars-sized object collided with the proto Earth. Subsequent to the impact, the surface of the Earth was molten, and the Moon formed from the debris that was thrown into Earth orbit. None of the scientific papers that I have read on other, but related, subjects seem to take that molten period into account. That brings up the question: when did that formation event occur? Thank you. George Prehmus