The early Earth was mixed with a baby planet called Theia following a head on collision 4.5 billion years ago, scientists have found
Earth is actually made up from two planets which came together in a head-on collision that was so violent it formed the Moon, scientists have concluded.
Initially it was believed that the Moon was created when a smaller planet called Theia grazed the Earth and broke up, sending a smaller chunk into space where it was caught in Earth’s gravity.
But if that was the case the Moon would have a different chemical composition to the Earth, because it would be made up, predominantly, of Theia.
However, after studying Moon rocks brought back by astronauts on the Apollo missions, scientists at the University of California have found that their oxygen isotopes are the same as on Earth.
It means that the collision between Their and the early Earth was so violent that the two planets effectively melded together to form a new planet, a chunk of which was knocked off to form the Moon.