New Clues to Earth’s Atmospheric Loss From Moon’s Origin From Planet Collision Supercomputer Simulations

Cross-section snapshots of 3D simulations of giant impacts using 30 to 100 million particles, coloured by their material or their internal energy, related to their temperature.
Credit: Jacob Kegerreis, Durham University

Earth could have lost anywhere between ten and 60 percent of its atmosphere in the collision that is thought to have formed the Moon.

New research led by Durham University, UK, shows how the extent of atmospheric loss depends upon the type of giant impact with the Earth.

Researchers ran more than 300 supercomputer simulations to study the consequences that different huge collisions have on rocky planets with thin atmospheres.

Their findings have led to the development of a new way to predict the 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 or other giant impacts.

They also found that slow giant impacts between young planets and massive objects could add significant atmosphere to a planet if the impactor also has a lot of atmosphere.

The findings are published in the Astrophysical Journal Letters.

Cross-section animation of the early stages of a 3D simulation of a head-on, slow giant impact using 30 to 100 million particles, colored by its material or its internal energy, related to its temperature.
Credit: Jacob Kegerreis, Durham University

The Moon is believed to have formed about 4.5 billion years ago following a collision between the early Earth and a giant impactor possibly the size of Mars.

Research lead author Dr. Jacob Kegerreis, in the Institute for Computational Cosmology, Durham University, 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.

“We ran hundreds of different scenarios for many different colliding planets, showing the varying impacts and 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 neighbor.”

Earlier this year, an initial study by Durham University reported that giant impacts that dominate the late stages of planet formation can have a wide range of consequences for young planets and their atmospheres.

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