() — Saturn’s iconic icy rings could cease to exist in the future for skygazers viewing them through their telescopes, according to new research.
A new analysis of data captured by NASA’s Cassini mission, which orbited the gas giant planet between 2004 and 2017, has revealed new insights into how long the rings have existed and when they might fade from view. The findings were shared in three studies published in May.
Our solar system and its planets formed about 4.6 billion years ago, and scientists have long debated the age and origin of Saturn’s rings. Some astronomers argue that the bright, icy rings must be younger than expected because they have not been eroded and darkened by meteoroid interactions over billions of years.
The Cassini data has led to a new finding, published May 15 in the academic journal Icarus, which supports this theory that the rings appeared long after Saturn’s initial formation. Other studies published May 12 in Science Advances and on May 15 in Icarusrespectively, reached similar conclusions.
“Our inescapable conclusion is that Saturn’s rings must be relatively young by astronomical standards, just a few hundred million years old,” said Richard Durisen, professor emeritus of astronomy at Indiana University Bloomington and lead author of both studies. published in Icarus, in a statement.
“If we look at Saturn’s satellite system, there are other indications that something spectacular happened there in the last hundreds of millions of years. If Saturn’s rings are not as old as the planet, that means something happened to form its incredible structure, and that’s very exciting to study.”
According to the researchers, it is likely that the seven rings were still in formation when dinosaurs roamed the Earth.
Saturn’s rings
Saturn’s rings are made mostly of ice, and only a small percentage is rocky dust created in space by broken fragments of asteroids and micrometeoroids. These sand-like fragments collide with particles from Saturn’s rings and create floating debris as the ring material orbits the planet.
During Cassini’s grand finale, when the spacecraft completed 22 orbits passing between Saturn and its rings, the researchers were able to obtain data on how many meteoroids contaminate the rings, the mass of the rings themselves, and the speed at which material from the rings rain down on the planet. All the data seemed to point to the same conclusion about the youngerness of Saturn’s rings.
Saturn’s rings are made up of ice particles the size of grains of sand or rocks. The ring system extends up to 282,000 kilometers from the planet. Credit: NASA/JPL-Caltech/Space Science Institute
The researchers managed to determine the amount of cosmic dust that accumulates in the icy rings. Over 13 years, Cassini’s Cosmic Dust Analyzer was able to collect 163 dust grains from beyond the Saturn system as they orbited the gas giant. The rings were surprisingly “clean,” suggesting that they must not have been around for so long as to accumulate excess cosmic dust.
Meanwhile, as meteoroids infiltrate the rings, they push material from the innermost rings toward Saturn at high speeds. Cassini observed that the rings were losing many tons of mass per second, which means they don’t have much time left, astronomically speaking. The researchers estimate that the rings will only last a few hundred million years at most.
Previous research had suggested that the rings could disappear in 100 million years.
enduring mysteries
“We have shown that colossal rings like Saturn’s don’t last very long,” said Paul Estrada, a research scientist at NASA’s Ames Research Center in Mountain View, California, and co-author of the three studies.
“It can be speculated that the relatively faint rings surrounding other gas and ice giants in our solar system are remnants of rings that were once colossal like those of Saturn. Perhaps sometime in the not too distant future, astronomically speaking , after Saturn’s rings shrink, they will look more like the sparse rings of Uranus.”
Cassini captured a backlit view of Saturn while it was in the planet’s shadow in December 2012.
Credit: NASA/JPL-Caltech/Space Science Institute
The dark rings around Neptune and Uranus may have been larger and brighter in the past, similar to how Saturn’s rings are now, the researchers said.
But what caused Saturn’s rings? Scientists don’t know for sure yet, but it’s possible that gravitational instability destroyed some of the icy moons orbiting the giant planet, creating enough material to be swept away to form the rings of material that encircle Saturn.
“The idea that Saturn’s iconic main rings could be a recent feature of our solar system has been controversial, but our new results complete a trifecta of Cassini measurements that make this finding hard to deny,” he said in a statement. Researcher Jeff Cuzzi, Principal Investigator at NASA Ames and co-author of the Saturn research paper that appeared in Science Advances.
Future missions to study some of Saturn’s moons could reveal more information about what events created the rings, and lead to other discoveries.
“If we can figure out what happened in that system a few hundred million years ago to form the rings, we may eventually discover why Saturn’s moon Enceladus is spewing plumes of water, ice, and even organic material from its deep ocean.” Durisen said. “We may even end up finding the building blocks of life itself on Enceladus.”
