Unlocking the mystery of the Moon’s formation

(4 December 2020)

Supercomputer simulations could unlock mystery of Moon’s formation

We’re using supercomputer simulations to see how the Moon might have formed following a huge collision involving the early Earth 4.5 billion years ago.

Durham is home to some of the world’s leading space scientists and most powerful supercomputer technology.

Our astronomers have used this combined knowledge and tech to investigate how the Moon might have been created.

Solar system

In their computer simulations, they crashed a Mars-sized ancient planet called Theia – which is believed to have existed in our solar system – into the early Earth.

They got different outcomes depending upon the size and direction of the spin given to Theia, including no spin at all.

At one extreme, the collision merged the two objects together while at the other there was a grazing hit-and-run impact.

Importantly, when no spin was added to Theia the collision produced a self-gravitating clump of material with a mass of about 80 per cent of the Moon. Another Moon-like object was created when a small amount of spin was added.

Potential Moon

Our researchers say this clump, which in the simulations is seen settling into an orbit around the post-impact Earth, would grow by sweeping up the disc of debris surrounding our planet.

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

Our researchers are careful to say that this isn’t definitive proof of the Moon’s origin, but add that it’s a very interesting place to continue looking.

They plan to run further simulations altering the mass, speed and spinning rate of both the early Earth and Theia to see what effect this has on the formation of a potential Moon.

Find out more

• The research is published in Monthly Notices of the Royal Astronomical Society.

• PhD research student Sergio Ruiz-Bonilla in our Institute for Computational Cosmology and Department of Physicsled the research.

• The latest research was carried out with Durham’s Institute for Data Science and the School of Physics and Astronomy at the University of Glasgow, UK.

• The high-resolution simulations were conducted on the COSMA supercomputer, part of the DiRAC High-Performance Computing facility based in Durham. The research used the SWIFT open-source code, largely developed and maintained at Durham.

• The research was funded by the Science and Technology Facilities Council, part of UK Research and Innovation.

• See more about how we’re investigating the impact of giant planetary collisions.

• Interested in studying Physics at Durham? See undergraduate and postgraduate opportunities.