A new theory has emerged where the moon was actually formed by several small collisions, rather than one large one. Credit: The Weizmann Institute of Science.
A new theory has shed some doubt as to how the moon was created, rejecting a popular theory that it was born through a single giant collision.
In a new study, researchers at the Weizmann Institute of Science ran about 800 simulations on a computer cluster, and determined that the moon was formed by a number of run-ins with smaller objects rather than one large collusion.
The researchers theorized that this type of activity would have produced smaller moonlets that would have eventually coalesced into a larger, singular moon.
The most prominent theory regarding how the moon was created involved an impact between a Mars-sized object and a young Earth.
In the study, professor Oded Aharonson and research student Raluca Rufu argue that the accepted theories for the formation of the moon rely on highly specific initial conditions like a collision with an object of a particular size traveling at a defined velocity and hitting Earth as a specific angle.
The researchers also said that 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.
However, various chemical analyses of the Moon’s makeup taken from sample returned by astronauts show that it is nearly identical to that of Earth, meaning there is no trace of the large body that supposedly hit Earth.
According to Aharonson, if a number of different bodies collided with Earth over millions of years, their different chemical signatures— like the ratios of oxygen-16 to oxygen-17-and-18— might even out, masking the traces of the various collisions.
However, if the moon was formed by several smaller collisions, with objects ranging from small planets to space rocks the size of the moon, the collision would have sent clouds of rubble, melt and vapor into orbit around the early Earth.
According to the recent simulations, these clouds would have cooled and agglomerated into small moonlets that in time could have merged into one moon.
“The new scenario does not require finely tuned initial conditions,” Rufu said in a statement. “And if the smaller moonlets, as we think, were drawn into the same orbit, they could have merged over millions of years.”
Aharonson said the researchers will continue to run simulations in an attempt to learn how the moon was formed.
“We are now running further simulations to try to understand how the smaller moonlets produced in these simulations might have coalesced to form our Moon,” he said in a statement.
The study was published in Nature Geoscience.
