12 January, 2017
Our Solar System is thought to have formed 4,567 billion years ago, followed by the Moon about 100 million years later.
"Our model suggests that the ancient Earth once hosted a series of moons, each one formed from a different collision with the proto-Earth", said co-author of the study, Prof.
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. Earth experienced many giant impacts with other bodies in its last stages of the growth. If Earth was indeed impacted by Theia, and later formed the moon out of the debris, then we should have found some Theia material, a.k.a. telltale isotopes, in the lunar samples. Oded Aharonson of Weizmann Institute's earth and planetary sciences department and Dr. Hagai Perets of the Technion.
The moon is the most obvious and familiar object in Earth's night sky - constant, consistent, predictable in its monthly cycles and its daily rising and setting. The new hypothesis claims that an estimated 20 objects, with the same size as the moon or Mars, struck the Earth and flung debris from the planet into orbit. The resultant collision threw vaporized chunks of the Earth's crust into space and the ejected material was bonded to form the moon under the planet's gravitational pull.
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To check the conditions for the formation of such mini-moons or moonlets the researchers ran 800 simulations of impacts with Earth. The moon, it seems, may have been formed not from a single collision, but a whole series of them, all in one brief, chaotic period in the solar system's history.
This version of the moon's origin story solves the big chemistry question that dogs proponents of the giant impact model. The impact from this collision most likely formed the Moon. 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. "One giant impact should produce a more homogenous rock, but under our scenario, I'd expect the composition to vary between different regions".
A new theory out suggests everything we know about the moon is wrong and that it's actually made of several smaller moons. It showed that the rocks were closely identical to those on Earth in terms of composition and there was no trace of the impacting asteroid on the rocks. Although that scenario is possible - some scientists suspect that Theia formed near Earth - researchers from the Weizmann Institute of Technology and the Technion-Israel Institute of Technology believe that the chances are slim.
Mr Rufu added: "It's likely that small moons formed through the process could cross orbits, collide and merge".