Scientists believe Earth once had two moons, and one of them might still be with us, just not the way you think. The theory suggests that a second smaller moon orbited Earth alongside our current one, but one day they collided. The crash didn't destroy the main moon. Instead, it splattered the smaller one across its far side. That could explain why the moon's near side is smooth and dark, while the far side is thicker, rougher, and mysteriously different. In a way, our moon might be the survivor