Recent studies on the lunar soil and rocks collected during the Apollo missions might be enough to disprove the old theory on the formation of the moon. The former hypothesis stated that the moon, 4.5 billion years ago, formed after a ‘giant impact’ between the early Earth and a planet the size of Mars.
If this theory were true, the moon should be formed in a large percentage from the same materials as the planet that collided with Earth. Studies showed that the moon’s surface is surprisingly similar to Earth. This was possible only if the colliding planet had the same Earth-like surface.
A new study regarding the origin of the moon challenges the former single-impact hypothesis. The new theory suggests that the moon was not formed from a single impact, but when many other smaller impacts created smaller bodies. These bodies, called “moonlets”, merged into one single object that today is the moon.
The lead author of the study, Raluca Rufu, of the Weizmann Science Institute in Rehovot, explained how the second moon-formation hypothesis is more plausible. They ran several simulations of the collision on advanced computer programs and found that a single impact most surely did not happen under standard conditions. The initial hypothesis required that the collision should have taken place at a certain speed, the body was supposed to have had a particular size and hit the Earth under a specific angle. All of these were most unlikely to have been true.
The simulations they ran concerning the new hypothesis showed that, after numerous collisions, clouds of rubble were eliminated around the early Earth. These were bound to have formed the moonlets that, later on, gathered under the form of today’s moon. Also, after millions of years after the collisions, the surface and chemical compositions of the moonlets may have become homogeneous, thus hiding the signs of early clashing.
Other simulations are now run in order to provide an explanation for how the moonlets merged to form the moon.
The several-impact hypothesis is not novel. It has been proposed in the 1980s too, but the lack of evidence and the poor explanation of the process caused the theory to be dismissed. The present paper is meant to make other researchers perform experiments and calculations in order to reach a conclusion regarding the formation of the moon.
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