Saturn's famous rings younger than previously thought, study reveals

Researchers analyse cosmic dust to unravel the youthful age of gas giant's rings, yet their origins remain a mystery

Saturn's seven rings are primarily composed of innumerable ice chunks with small quantities of rocky material. PA

The rings of Saturn, one of the most famous sights in the solar system, are a mere 400 million years old, substantially younger than the four-billion-year-old planet itself, a study has found.

The discovery adds a fresh twist to the enduring mystery surrounding the origins of these celestial formations.

The study was led by researchers who analysed data obtained from Nasa's Cassini spacecraft.

Cassini, which met its end in a controlled crash in 2017, collected invaluable data about the solar system during its mission, including information about the minuscule grains of rocky material that traverse the vast expanse of space.

These tiny dust particles, the researchers explained, occasionally leave a thin residue on celestial bodies as they journey through the cosmos.

This residue can be found on the icy formations that constitute Saturn's rings.

By studying the rate at which this cosmic dust accumulates, the team was able to estimate the age of the rings.

This methodology is similar to estimating the age of a building by examining how much dust has gathered on its surfaces over time.

“We think the rings have been collecting dust for a few hundred million years,” said Sascha Kempf, an associate professor in the Laboratory for Atmospheric and Space Physics at the University of Colorado Boulder.

Dr Kempf likened the process to dust settling on a carpet.

“If you have a clean carpet laid out, you just have to wait. Dust will settle on your carpet. The same is true for the rings.”

Saturn's seven rings are primarily composed of innumerable ice chunks with small quantities of rocky material.

The ice extends more than 280,000 kilometres from the planet's surface, but its total mass is almost 5,000 times less than that of Earth's Moon.

The rings of Saturn were first observed by Italian astronomer Galileo Galilei in 1610. Their origins, however, have remained elusive.

In the 19th century, Scottish physicist James Clerk Maxwell deduced that the rings were composed of numerous individual pieces rather than solid, concentric circles.

The team of researchers for this study inspected data from Cassini's Cosmic Dust Analyser instrument, studying 163 dust grains originating from beyond Saturn's immediate vicinity.

Their findings, published in the journal Science Advances, provide the most compelling evidence to date that Saturn's rings are youthful.

This contradicts the previously held belief that the rings were as old as the planet itself, estimated to be about 4.5 billion years old.

“We've got closure on a question that started with James Clerk Maxwell,” said Dr Kempf.

There is mounting evidence that the rings may already be disappearing, with previous Nasa research suggesting that ice from the rings is slowly falling on to Saturn's surface, potentially leading to their complete dissipation in another 100 million years.

As for the question of how these rings formed initially, Dr Kempf conceded: “We know approximately how old the rings are, but it doesn't solve any of our other problems. We still don't know how these rings formed in the first place.”