Co-author Hagai Perets of the Technion, Israel Institute of Technology in Haifa, said: "Our model suggests that the ancient Earth once hosted a series of moons, each one formed from a different collision with the proto-Earth".
Apollo's Alan Shepard and Edgar Mitchell collected rocks and used tubes to dig up soil while exploring the moon's Fra Mauro highlands in February 1971. In this theory, about a fifth of the Moon's material would have come from Earth and the rest from the impacting body.
"T$3 he composition similarity between the Earth and the moon in the giant impact can not be explained without using a special Earth-like impactor", said lead author Raluca Rufu, a researcher at the Weizmann Institute of Science in Israel, according to Space.com. As a result, tiny moons were formed from these impact that when combined together over millions of years, they form into one giant moon which we see most of the nights.
The moon, it turns out, is surprisingly Earth-like in its composition, and this, many scientists say, would only be possible if the giant impactor was made of exactly the same material as Earth.
Now, a team of Israeli researchers has shaken up the debate by offering an entirely new explanation, published this week in the journal Nature Geoscience. However, because the Earth and Moon are so similar in their makeup, this theory has been steadily losing ground. They found the impacts produced small discs, which formed small moons or "moonlets". "A long series of such moon-moon collisions could gradually build up a bigger moon - the Moon we see today", he added.
There's a problem with this single-impact hypothesis, though.
During the study, the authors ran 800 simulations of impacts to recreate the conditions that created moonlets.
For the Moon to be as Earth-like as it is, a single impactor would have had to have a very Earth-like composition, she said. The tidal forces from Earth cause moonlets to slowly migrate outwards, But their mutual gravitation attraction eventually causes the moonlets to affect each other, change their orbits and form the Earth's satellite with its present characteristics. "This paper shows that moonlets can be commonly formed, therefore the lack of moons around Venus is an interesting follow up question of how planets can sometimes lose their moons".
Still, there's not enough data to confirm the multi-collision theory, and it seems that more studies will follow.
About 20 moonlets colliding and merging over millions of years could have formed the moon, according to a new theory suggested by research from the Weizmann Institute of Science.
It is now being further explored by a colleague of Rufu's at the Technion, Israel's Institute of Technology.
Small collisions like this were common in the early solar system, and support their premise.