Giant impact could have formed the Moon more rapidly, scientists reveal in new simulations

Scientists from Durham University's Institute for Computational Cosmology used the most detailed simulations yet to reveal an alternative explanation for the Moon's origin.

The calculations were done using the open-source simulation code that was hosted by Durham University on behalf of the DiRAC High- Performance Computing facility.

Researchers were able to discover features that weren't available in previous studies because of the extra computational power. The outer layers of the Moon-like satellite were richer in material from the Earth.

If a lot of the Moon formed immediately after the giant impact, this could mean that less molten was created than in the standard theories where the Moon grew within a debris disk. The internal structures for the Moon should be predicted by the theories.

The formation route could help explain the similarities between lunar rocks and Earth's mantle. The thickness of the lunar crust may have an effect on the type of collision that happened.

When a satellite passes so close to the Earth that it might be torn apart by the " tidal forces " from Earth's gravity, the satellite can not only survive, but also be pushed onto a larger, safer path.

Jacob Kegerreis said that this opens up a whole new range of possible starting places for the evolution of the Moon. We didn't know what the outcome of the simulations would be. On top of the fact that standard resolutions can give you wrong answers, it was even more exciting that the new results could include a moon-like satellite.

The Moon is thought to have formed after a collision between the young Earth and a Mars-sized object. The Moon is created by gradual accretion of the debris. This has been challenged by the fact that lunar rocks have the same composition as Earth's mantle and that the impact produces debris from Theia.

The predicted composition and internal structure of the Moon could be improved by this immediate-satellite scenario. New clues about what kind of impact led to the Moon should be revealed by the upcoming lunar missions.

The results of the research were published in the Astrophysical Journal Letters.

More information: J. A. Kegerreis et al, Immediate origin of the Moon as a post-impact satellite, Astrophysical Journal Letters (2022). www.hou.usra.edu/meetings/lpsc2022/pdf/1724.pdf Journal information: Astrophysical Journal Letters