There is a new theory for the formation of the Moon (and this one makes more sense)

Conventionally, the Moon is thought to have formed during a large impact. However, a new model argues that three impacts on Earth can better explain the origin than a single giant impact 4.5 billion years ago.

Determining the origin of our Moon has been difficult. The main idea is that it was formed early in the history of the solar system, following an impact between Earth and a gigantic Mars-sized object known as Theia, which possibly originated closer to the Sun than where our planet is.

As described by , the impact would have thrown debris into space that eventually coalesced into the large natural satellite we see today, at a time when material was more mixed around the Sun and impacts were common.

But the Earth and the Moon are surprisingly similar in composition, which makes this model a bit difficult because the Moon should have retained more material from Theia than the Earth.

“This is a big problem for the canonical model”, he says Philip Carterfrom the University of Bristol, United Kingdom, who was part of the new study, at the end of October at Monthly Notices of the Royal Astronomical Society.

Instead, Carter and his colleagues propose that a chain of impacts on Earth over a few million years may better explain why our planet and the Moon are so similar in composition.

They show that three or more major impacts on our planet in the early solar system, involving objects that ranged from the current size of the Moon to almost the size of Mars, could explain the origin of the Moon we see today.

In this scenario, each impact would produce a small moonor “luete”, in Earth orbit.

Over thousands of years, these luettes would gradually combine with each other under their gravity, forming a single large object.

Previous models also invoked a multiple-impact origin for the Moon, but required a much greater number of impacts on Earth, up to 20, compared to this newer model.

“After three impacts, we put enough mass into orbit to form a complete Moon,” said Carter, quoted by New Scientist.

To the same magazine, Robert Citronfrom the Southwest Research Institute in Colorado, who was not part of the investigation, says that having fewer impacts “may be better” because the more impacts a model has, the greater the likelihood that existing luets will be expelled from Earth’s orbit, preventing the formation of the Moon.