Supercomputer simulations could unravel the mystery of Moon’s formation

Astronomers have taken a step towards understanding how the Moon could have formed from a giant collision between the early Earth and another huge object 4.5 billion years ago.

Scientists led by Durham University, UK, ran supercomputer simulations on the DiRAC high-performance computing facility to send a Mars-sized planet called Theia crash into early Earth.

Their simulations produced an orbiting body that could potentially evolve into a moon-like object.

Although the researchers are careful to say that this is not definitive proof of the Moon’s origin, they add that it could be a promising stage for understanding how our closest neighbor would have formed.

The results are published in the journal Royal Astronomical Society Monthly Notices.

The Moon is thought to have formed in a collision between early Earth and Theia, which scientists believe may be an ancient planet in our solar system, about the size of Mars.

The researchers ran simulations to track material from early Earth and Theia for four days after their collision, then ran other simulations after spinning Theia like a billiard ball.

The simulated collision with the primeval Earth produced different results depending on the size and direction of Theia’s initial rotation.

At one extreme the collision fused the two objects together, while at the other a radical impact occurred.

Importantly, the simulation in which no spin was added to Theia produced a self-gravitating mass of material with a mass of about 80% of the Moon, while another Moon-like object was created when it was added. a small amount of spin.

The resulting mound, which settles into an orbit around the Earth after impact, would grow and sweep away the disc of debris surrounding our planet.

The simulated group also has a small iron core, similar to that of the Moon, with an outer layer of materials consisting of the early Earth and Theia.

A recent analysis of the oxygen isotope ratios in lunar samples collected by the Apollo space missions suggests that a mixture of early Earth and impact material may have formed the Moon.

Lead author Sergio Ruiz-Bonilla, Ph.D. researcher at the Institute for Computational Cosmology at Durham University, said, “By adding different amounts of spin to Theia in the simulations, or by not having any spin, you get a whole range of different results for what could have happened when the early Earth was hit by a huge object all those billions of years ago.

“It is exciting that some of our simulations have produced this mass of material in orbit relatively not much smaller than the Moon, with an additional disk of material around the Earth after impact that would help the group grow in mass over time.

“I wouldn’t say this is the Moon, but it’s certainly a very interesting place to keep looking.”

The Durham-led research team now plans to run further simulations that alter the mass, velocity, and rotational speed of both the target and the impactor to see what effect it has on the formation of a potential Moon.

Co-author Dr. Vincent Eke, of the Institute of Computational Cosmology at Durham University, said, “We get a number of different results depending on whether or not we introduce the spin to Theia before it crashes to the early Earth.

“It is particularly fascinating that when no or very little spin is added to Theia, the impact with early Earth leaves behind a trail of debris, which in some cases includes a body large enough to deserve to be called proto-Moon.

“There may be a number of possible collisions that have yet to be studied that could bring us even closer to understanding how the Moon formed.”