Scientists believe that the moon may have formed after multiple rocky bombardments that struck the Earth, sending trillions of tonnes of debris into orbit.
Simulations show that over a 100m years, impacts could have kicked up enough material to form moonlets that eventually fused together to make the moon.
According to researchers at the Weizmann Institute of Science in Israel, around 20 rocky bodies, some as large as the moon is now and Mars, would have been enough to do it.
The theory goes against the currently held belief that a Mars sized object hit the Earth in a glancing blow, causing 70 billion billion tonnes of rock into space. This theory has raised questions of its own. If the moon was caused by one collision rather than several, then trace elements of the colliding object should be found on the moon. So far, none have been found.
It has been suggested that the body that crashed into the Earth was of the same chemical composition. Analysis of meteorites and other bodies show that in comparison to the Earth and moon, meteorites chemical makeup varies substantially.
Raluca Rufu, author of a study into how the moon was made, ran a series of computer simulations to see if multiple hits could have formed the moon.
He said, “We see that multiple impacts will have a high probability of building a moon with similar composition to the Earth. With 20 impactors, it would take about 100m years to build the moon.”
The scientist continued, “As a scientist you always have to ask ‘is it true or not?’ If you have too much confidence in your theory something is wrong.”
Whether or not her theory is true, the answer may be revealed when China sends Chang’e 5 to the moon and brings back more rock for analyses.