Saturn’s rings are dated at 400 million years

May 12. (EUROPE PRESS) –

New research pegs the age of Saturn’s rings at no more than 400 million years, much younger than Saturn itself. which is about 4.5 billion years old.

That’s the conclusion of a new study, led by University of Colorado physicist Sascha Kempf, that answers a question that has stumped scientists for more than a century.

The work, which is published in the journal ‘Science Advances’, focused on analyzing the dust. Kempf explains that tiny grains of rocky material traverse Earth’s solar system almost constantly. In some cases, this flow can leave behind a thin layer of dust on planetary bodies, including the ice that forms Saturn’s rings.

In the new study, he and his colleagues set out to date Saturn’s rings by studying how quickly this layer of dust accumulates, sort of like finding out how old a house is by running your finger across its surface.

“Think of the rings as the carpet in your house,” Kempf says. “If you have a clean carpet, you just have to wait. The dust will settle on the carpet. The same goes for the rings.”

From 2004 to 2017, the team used an instrument called the Cosmic Dust Analyzer aboard NASA’s defunct Cassini spacecraft to analyze dust specks flying around Saturn.

During those 13 years, the researchers collected just 163 grains that had originated beyond the planet’s near vicinity. But it was enough. According to his calculations, Saturn’s rings have probably collected dust for only a few hundred million years.

In other words, the planet’s rings are new phenomena, arising (and potentially disappearing) in the blink of an eye in cosmic terms. “We know roughly how old the rings are, but that doesn’t solve any of our other problems,” Kempf says. We still don’t know how these rings formed.”

Researchers have been captivated by these apparently translucent rings for more than 400 years. In 1610, the Italian astronomer Galileo Galilei first observed them through a telescope, although he did not know what they were. Galileo’s original drawings make the rings somewhat resemble the handles of a water jug.

In the 19th century, James Clerk Maxwell, a Scottish scientist, concluded that Saturn’s rings could not be solid, they were made up of many individual pieces.

Scientists now know that Saturn is home to seven rings made up of countless chunks of ice, most of them no bigger than a rock on Earth. In total, this ice weighs half as much as Saturn’s moon Mimas and extends some 280,000 kilometers from the planet’s surface.

Kempf adds that, for most of the 20th century, scientists assumed that the rings probably formed at the same time as Saturn, but that idea raised some questions, such as that the rings are ‘clean’. Observations suggest that they are made up of 98% water ice by volume, with only a small amount of rocky matter. “It is almost impossible to finish with something so clean”, says Kempf.

‘Cassini’ offered the opportunity to put a definitive age on Saturn’s rings. The spacecraft first arrived at Saturn in 2004 and collected data until it intentionally crashed into the planet’s atmosphere in 2017. The cube-shaped Cosmic Dust Analyzer it picked up tiny particles as they whizzed by.

Engineers and scientists at LASP (Laboratory for Atmospheric and Space Physics) designed and built a much more sophisticated dust analyzer for NASA’s upcoming Europa Clipper mission, scheduled to launch in 2024.

The team estimated that this interplanetary debris would contribute much less than a gram of dust to each square meter of Saturn’s rings each year—a slight pinch, but enough to accumulate over time. Previous studies had also suggested that the rings could be young, but they did not include definitive measurements of dust accumulation.

The rings could be disappearing already. In an earlier study, NASA scientists reported that ice is slowly falling on the planet and could disappear completely in another 100 million years.

According to Kempf, that these ephemeral features existed at a time when Galileo and the Cassini spacecraft were able to observe them seems too good to be true, and demands an explanation of how the rings formed in the first place.

Some scientists, for example, have posited that Saturn’s rings might have formed when the planet’s gravity tore at one of its moons. “If the rings are short-lived and dynamic, why are we seeing them now? It’s just too lucky,” Kempf concludes.