The moon may have been created by several moonlets forming together rather than an impact hitting the Earth, scientists believe. Computer simulations examining thousands of scenarios have determined it would have taken about 20 mini-moons to create the one that orbits the Earth. The researchers, from Israel, say the process may have taken millions of years.
Our model suggests that the ancient Earth once hosted a series of moons, each one formed from a different collision with the proto-Earth.
Hagai Perets of the Technion, Israel Institute of Technology in Haifa
It was previously believed that the moon was formed when a giant asteroid collided with the earth, knocking off a piece of it that ultimately failed to escape the Earth’s gravity. The scientists say the latest theory could explain why the moon appears to be made of material from Earth and not from outer space. It was assumed that some of the asteroid would have remained attached to the piece that ended up in orbit.