Astronomers say they are one step closer to understanding how the moon might have formed out of a giant collision between the early Earth and another massive object 4.5 billion years ago. The moon is thought to have formed in a collision between the early Earth and a huge object, known by scientists as Theia. Scientists at the University of Durham ran supercomputer simulations to send a Mars-sized object crashing into the early Earth. These simulations produced an orbiting body that could potentially evolve into a moon-like object. While the researchers are careful to say this is not definitive proof of the moon’s origin, they add that it could be a promising stage in understanding how the celestial body formed.