Rocky Planet Simulations give clues to Moon’s Origin

A study using the Science and Technology Facilities Council-funded DiRAC High-Performance Computing facility at Durham University has helped scientists to simulate more than 300 huge collisions on rocky planets with thin atmospheres, similar to the one thought to have formed the Moon and cause Earth to lose between 10 to 60 percent of its atmosphere. The simulations, which were run using the SWIFT open-source simulation code and carried out on the COSMA supercomputer, have helped develop a new way to predict atmospheric loss from any collision across a wide range of rocky planet impacts that could be used by scientists who are investigating the Moon’s origins.

Research lead author Dr Jacob Kegerreis, in the Institute for Computational Cosmology at Durham, said: “The puzzle about how the Moon formed and the other consequences of a giant collision with the early Earth is something that scientists are working hard to unravel. Modelling these violent collisions is already a numerical challenge, but the low density of an atmosphere compared with the rest of the planet requires orders of magnitude higher resolution than typical simulations.

“The DiRAC facility's large Memory Intensive system, combined with the game-changing SWIFT hydrodynamics and gravity code allowed us to run high-resolution simulations of hundreds of different scenarios for many different colliding planets, showing the varying effects on a planet’s atmosphere depending upon a number of factors such as the angle, speed of impact or the sizes of the planets.

“While these computer simulations don’t directly tell us how the Moon came to be, the effects on the Earth’s atmosphere could be used to narrow down the different ways it might have been formed and lead us closer to understanding the origin of our nearest celestial neighbour."