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Saturn's rings may have formed after two icy moons collided

The mysterious origin of Saturn’s rings may finally be revealed. A team of researchers suggests that the rings evolved from the debris of two icy moons that collided a few hundred million years ago. 

Supercomputer simulations 

For their investigation, the experts used a new series of high-resolution supercomputer simulations. The research sheds light on why the rings appear significantly younger than the planet itself.

The simulations also provide a plausible explanation for the formation of Saturn’s rings. 

Collision scenario

“We tested a hypothesis for the recent formation of Saturn’s rings and have found that an impact of icy moons is able to send enough material near to Saturn to form the rings that we see now,” said Dr. Vincent Eke from Durham University

The proposed collision scenario involves the progenitor moons smashing into one another, leading to the dispersal of the rock in their cores less widely than the overlying ice, consequently forming ice-rich rings.

Ring composition

These findings help to clarify the composition of Saturn’s rings, which Cassini spacecraft data revealed to be almost pure ice with minimal dust pollution. 

Cassini, which orbited Saturn for 13 years beginning in 2004, provided invaluable data by passing and diving through the gap between Saturn and its rings, capturing precise details about the planet and its surrounding system. 

The nearly pure icy composition of the rings suggests their formation occurred relatively recently in the life span of the solar system. 

How the study was conducted 

The collaborative research effort involved scientists from NASA, Durham University, and Glasgow University. 

The team simulated various collision scenarios between precursor moons at a resolution over 100 times higher than previous studies, offering unprecedented insights into the Saturn system’s history. 

Saturn’s Roche limit 

Through nearly 200 different versions of simulated impacts, the researchers found that numerous collision scenarios could feasibly scatter adequate amounts of ice into Saturn’s Roche limit, eventually settling into rings resembling those observed today. 

The Roche limit represents the maximum orbit distance where a planet’s gravitational pull can disintegrate larger bodies of rock or ice drawing closer. Material orbiting beyond this limit might aggregate to form moons.

Study implications 

The in-depth simulations and their results provide a convincing explanation for the icy purity of Saturn’s rings. 

Considering that other elements of the planet’s system have a mixed ice-and-rock composition, alternative theories struggled to account for the minimal rock content in the rings. 

Fascinating results 

Dr. Jacob Kegerreis is a Durham University graduate who is now a research scientist at NASA’s Ames Research Center in California’s Silicon Valley. 

“There’s so much we still don’t know about the Saturn system, including its moons that host environments that might be suitable for life, so it’s exciting to use big simulations like these to explore in detail how they could have evolved,” said Dr. Kegerreis.

“The apparent geological youth of Saturn’s rings has been a puzzle since the Voyager probes sent back their first images of the planet,” said Dr. Luis Teodoro from the University of Glasgow.

“This collaboration has allowed us to examine the possible circumstances of their creation, with fascinating results.” 

More about Saturn’s rings

Saturn’s rings are a prominent feature of the planet, made up of countless small particles ranging from tiny, dust-sized icy grains to larger debris several meters across. These particles are predominantly composed of water ice with traces of rocky material. 

Orbit of the rings

The rings orbit around Saturn at various distances, creating distinct bands or rings. Each ring orbits at a different speed and has varying widths and thicknesses.

Naming system

The rings have been named in the order they were discovered, leading to a non-sequential naming system. 

The main rings are, from nearest to furthest from Saturn, the D, C, B, A, F, G, and E rings. The gaps between the rings also have names, such as the Cassini Division, which is the dark area between the B and A rings.


The origin of Saturn’s rings is still a subject of research and debate among scientists. 

The current study suggests they are remnants of shattered moons, while other experts believe they may have formed along with Saturn itself. 

The findings are published in The Astrophysical Journal.

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