the moon IS THE OBJECT that hit us , think about it , its too big to stay ON the surface , its too big to move away from our pull.
Now, Andreas Reufer, of the Center for Space and Habitability in Bern, Switzerland, and colleagues have run computer simulations that suggest another possibility: that a far larger and faster-moving body made an even more glancing blow with the young Earth.
Not that I ever put credence into Nibiru or Planet X, this is quite a blow to that belief. Now I am not saying "Here it comes! Arghhhh!", as I am sure we would have detected such a body (whatever its composition), but it does go some way to backing the theory of a "wandering" planet, or a planet with a super long orbit, or whatever.