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AstrophysicsThe Moon Could Have Formed Within Hours
A new study evokes, simulation in support, the formation much faster than imagined of our satellite following the collision of Théia with the Earth.
Following the collision of the Earth with Theia most of the debris would have agglutinated to the Earth while the rest formed the Moon.
NASA’s Ames Research Center/YouTube
The Moon was formed billions of years ago when a Mars-sized planet called Theia collided with Earth. According to most scientific theories, the melting of the debris in orbit would have taken months or even years to form our satellite. But a new study suggests it would have taken only a few hours.
The composition of the Moon is very similar to that of the Earth, as shown by the samples of its soil brought back by the Apollo missions. Why then are there not more foreign elements, coming from Theia, in the composition of the Moon? Unless Theia herself was Earth-like, which is highly unlikely. The slow Moon formation theory involves essentially sputtering Theia in orbit, so the Moon should be different than it is.
Another theory, called synestia, supposes that the Moon formed in a cloud of vapor coming from the Earth following the giant collision, minor satellites coming together for years to end up forming the Moon. This explains the similar composition between Earth and Moon, but it hardly fits with the lunar orbit that we know.
An ultra-accurate computer simulation
NASA’s Ames Research Center in California’s Silicon Valley has performed a high-definition (i.e. with unprecedented computing power) simulation of the impact between Earth and Theia, as reported the NASA. And that made it possible to see a new behavior emerge. Material from both planets was launched directly into orbit following impact. If a good part came back to merge with the Earth, the rest quickly formed the Moon.
This scenario responds not only to the composition of the Moon but also to its orbit. Because it puts our satellite “into a wide orbit with an interior that isn’t completely melted, potentially explaining properties like the Moon’s inclined orbit and thin crust, making it one of the most compelling explanations. alluring for the origins of the Moon to date,” writes NASA.
The research has been published in «The Astrophysical Journal Letters» but we will have to wait for other analyses, such as those of future lunar samples brought back by the Artemis missions, to find out which theory is the most accurate. NASA points out that the more scientists can simulate and analyze what is at stake in space collisions, the more prepared we will be to understand how a planet might evolve to become habitable like our own Earth.