Saturn’s moon Enceladus drifting before the rings and the tiny moon Pandora, captured by NASA’s Cassini spacecraft. Image: NASA/JPL-Caltech/Space Science Institute
Saturn is famous for its vast, icy rings, but the latest research shows they are rapidly being sucked into the planet by its powerful gravitational field.
By far one of the most distinctive of the solar system’s array of planets, Saturn, with its famous rings, has long fascinated astronomers and the public alike. During the Voyager 1 and 2 flybys in the early 1980s, the satellites revealed a wealth of information about the planet, including how long its rings will last.
Now, NASA researchers have announced that new research into the planet shows it is losing its rings at such a rate that it is now deemed the “worst-case scenario” by astronomers.
Observations show the rings are being pulled into Saturn by gravity as a dusty rain of ice and particles influenced by the planet’s powerful magnetic field. Estimates suggest that the rings are draining water at such a rate that the volume could fill an Olympic-sized swimming pool every 30 minutes.
This alone should mean the rings would disappear 300m years from now but when you account for measurements from the Cassini spacecraft, which showed icy material falling into the planet’s equator, this means they have less than 100m years to live. As Saturn is a relatively young planet at 4bn years old, this is a very short lifespan for the rings.
NASA released a pretty amazing GIF of Saturn, showing the transition from what it looks like today to what it will look like towards the end of the rings’ lifespan.
An artist’s impression of how Saturn may look in the next 100m years. The innermost rings disappear as they rain on to the planet first, very slowly followed by the outer rings. Image: NASA/Cassini/James O’Donoghue
May have missed other solar system rings
The new findings, published to the journal Icarus, have helped find more clues to answering a ‘chicken and egg’ scenario of Saturn’s formation, that being whether Saturn formed with the rings or whether the planet acquired them later on. The findings suggest the latter to be true, meaning the rings are now older than 100m years old as it would take that long for the C-ring to become what it is today, assuming it was once as dense as the B-ring.
“We are lucky to be around to see Saturn’s ring system, which appears to be in the middle of its lifetime,” said James O’Donoghue of NASA’s Goddard Space Flight Center. “However, if rings are temporary, perhaps we just missed out on seeing giant ring systems of Jupiter, Uranus and Neptune, which have only thin ringlets today!”
Looking to the future, the researchers now want to see how the ring rain that falls to Saturn changes with the planet’s seasons. During its 29.4-year orbit, its rings are exposed to the sun to varying degrees. Since ultraviolet light from the sun charges the ice grains and makes them respond to Saturn’s magnetic field, varying exposure to sunlight should change the quantity of ring rain.
