Saturn's Rings Might Have Formed Millions of Years After the Dinosaurs Went Extinct

Scientists have discovered Saturn's rings are far younger than once thought, having formed as little as 10 million years ago. This is far, far later than the when Saturn itself first formed—around 4.2 billion years ago—and means the planet's iconic feature probably only appeared after the dinosaurs went extinct around 65 million years ago.

How Saturn ended up with rings is a longstanding mystery. They are composed almost entirely of water-ice and a small amount of rocky material. Scientists think they formed less than 100 million years ago when asteroids, comets and small moons got caught by the planet's gravitational pull and repeatedly collided, eventually being smashed into tiny bits.

Read more: Even more evidence points to alien life on Saturn's icy moon Enceladus

A recent study published in the journal Icarus suggested that Saturn's rings are a short-lived feature and they will be completely gone in around 300 million years. Researchers found the rings are losing mass at the maximum rate predicted, with the ice particles being dragged into the main body of the planet by gravity.

In a new study published in Science, a team of researchers led by Luciano Iess, from Italy's Sapienza University of Rome, have now used data from NASA's Cassini mission to produce new measurements of the gravitational field around Saturn and its rings. They used data from Cassini's "Grand Finale," where the spacecraft plunged through the planet's rings before burning up in the atmosphere below.

Before the Cassini mission, it was impossible to distinguish the gravitational effect of the rings from the main body of the planet. This mean the mass of the rings—which is linked to their age—could not be established.

"The relationship between the mass and age of the rings is subtle," Iess told Newsweek. He said there is a flux of "contaminant particles" present around Saturn that is sprayed onto the rings at a constant rate. By measuring the mass, they were able to estimate the total amount of deposited particles—and how long it took them to accumulate: 10 to 100 million years.

Researchers say the findings do not provide any details about how the rings formed. "A catastrophic event like a collision looks to me the most obvious explanation, but there may be problems with that too," Iess said. "I believe that the origin of the rings has to be put in the broader context of the dynamics of the Saturnian system."

Thomas Stallard, from the U.K.'s University of Leicester, who was not involved in the study, told Newsweek the results were "striking" as it "once again confirms a startling truth, that Saturn's rings have not existed in the solar system since the planet formed, but are relatively young."

saturn ring
Saturn and its rings. NASA/JPL-Caltech/Space Science Institute

He continued: "Although we don't yet know why, something catastrophic happened, perhaps in the age of the dinosaurs, that resulted in Saturn having a ring system completely unlike Jupiter and the ice giants Uranus and Neptune. But these rings, which are so iconic, are being eroded away. While, on human timescales, it seems that Saturn will always have its rings, across the lifetime of the solar system, these rings are set to quickly fade into obscurity."

James O'Donoghue, from NASA's Goddard Space Flight Center, said that the idea the rings formed around the time that the dinosaurs went extinct "is a profound result to end the Cassini mission… The more we learn about Saturn's rings, the more fragile and transient they seem to be."

Steve Miller, from University College London, U.K., said the findings reinforce the idea that we are living in "lucky times" by existing at the same time as the rings. "The breathtaking beauty of Saturn's rings is one of the delights of the night sky," he said. "We should enjoy it while it lasts."