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Ice moons after the crash (simulation): Solid components become liquid, splinters fly around

Photo: Durham University / Glasgow University / Jacob Kegerreis / Luís Teodoro / NASA / Youtube

Two icy moons and a fatal encounter: Saturn's iconic rings could have formed after a violent collision of two celestial bodies. This is the conclusion reached by a team of experts from the American space agency Nasa and Durham University, and the results have been published in the Astrophysical Journal.

A simulation developed by the group shows how the two icy moons approach each other piece by piece until it crashes. Solid components become liquid, splinters fly around. Eventually, the jumbled matter rearranges itself around Saturn and forms the known rings.

The resolution of the simulation is 100 times greater than the most accurate work of this kind so far, according to a statement on the study.

The team ran through almost 200 scenarios with different parameters. It turned out that a wide range of collisions between two icy moons could have led to the formation of Saturn's rings today. This theory could also explain why these consist almost exclusively of ice and contain almost no rock.

Splinters as part of new moons of Saturn

Saturn's rings can be seen from Earth with an amateur telescope when the sky is clear. And yet the planet is a mystery to astronomers. How did the rings come about? And when?

In May 2023, experts had reported that Saturn's rings could be just 400 million years old, significantly younger than the planet itself, which is 4.5 billion years old (read more here).

The current simulation coincides with this finding. It takes place a few hundred million years before our time, when dinosaurs still inhabited the earth. Fractions of the shattered icy moons that did not become part of the rings could now be installed in newer moons of Saturn.

"There's so much we don't know about the Saturn system, including its moons," said Jacob Kegerreis, a researcher at NASA's Ames Research Center. "So it's exciting to use large simulations like these to explore in detail how they might have evolved." Experts suspect that there could be life on some of the celestial bodies.

It is possible that flying icy moon parts would even have triggered a whole cascade of lunar collisions, writes the expert team. In the process, other early moons could have been destroyed, from which today's moons of the planet would have formed.

The question remains as to what led to the collision of the first two icy moons. The gravitational force of the sun could have played a role here, the research group suspects after their analysis. It may have given the icy moons additional momentum, so that their actually round orbits around Saturn got a dent and overlapped. Bang.

However, this does not conclusively settle the ring question.