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.
The research, which was published in the journal Nature Geoscience, runs counter to the previous theory that the moon was formed with the help of a giant asteroid that collided with Earth, knocking off a piece of the planet that failed to escape the Earth's gravity, Sky News reported.
The institute tested its scenario by running about 800 impact simulations on the Weizmann Institute of Science's Chemfarm cluster, which has more than 5,000 processor cores, according to a statement from the institute.
"The new scenario does not require finely tuned initial conditions and if the smaller moonlets, as we think, were drawn into the same orbit, they could have merged over millions of years," Raluca Rufu, a research student with the institute, said in the Weizmann statement.
The Nature Geoscience study said that in the institute's scenario, each moonlet collision would have formed a debris disk around the "proto-Earth" that would have formed a moonlet.
"The moonlets tidally advance outward, and may coalesce to form the moon," stated the Nature Geoscience abstract. "We find that sub-lunar moonlets are a common result of impacts expected onto the proto-Earth in the early solar system and find that the planetary rotation is limited by impact angular momentum drain. We conclude that, assuming efficient merger of moonlets, a multiple-impact scenario can account for the formation of the Earth–Moon system with its present properties."
Rufu and Weizmann professor Oded Aharonson stated that certain conditions would have been needed for the asteroid-strike theory to create the moon.
"… In a typical impact, different proportions of that object would have ended up in the Earth and the moon, leaving a detectable difference between the bodies," the Weizmann institute statement said. "But various chemical analyses of the moon's makeup, taken from samples returned by astronauts, reveal that it is nearly identical to that of Earth. In other words, there is no trace of the large body that supposedly hit Earth, and the theories, say the researchers, turn out to be improbable."
Rufu, Aharonson, and Hagai Perets of the Technion–Israel Institute of Technology, said smaller high-velocity collisions are a more likely scenario for the moon being formed and in light of how the solar system was formed several billion years ago, the institute's statement noted.
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