Scientists give Saturn's rings 100 million years to live
As strange as it sounds, the iconic rings that Saturn displays are more of a phase than a permanent feature. Like a teenager trying out a loud hairstyle or a middle-aged man dabbling in life with a goatee, this gas giant will someday outgrow its majestic ring system. A new NASA study has revealed it is shedding the material much faster than we realized, so much so its existence could one day come to resemble a tiny blip in the timeline of its entire life.
Scientists believe Saturn to be more than four billion years old, forming at the same time as the Solar System from a huge spinning disk of gases and particles. But when its rings entered the picture hasn't been entirely clear, with researchers uncertain if they formed alongside the planet or if they came to be much later on.
What we do know is these rings consist predominantly of water ice, with particles ranging in size from tiny dust specs to boulders measuring meters in diameter. These are naturally drawn in toward Saturn's surface by its gravitational field while their orbital velocity slings them outward, a delicate game of tug-of-war that suspends them in place. But for how much longer?
While all this is going on, the icy particles in Saturn's rings are electrically charged by the sun's UV rays and nearby plasma clouds. This causes them to react to Saturn's magnetic field and be pulled inward, where they rain down into the planet's ionosphere, part of its upper atmosphere.
Here, a chemical reaction takes place that causes the icy particles to glow in infrared light, a useful property for scientists using advanced imaging instruments to track their movements. Using the Keck telescope in Hawaii, scientists were able to gather images that illustrate the glowing particles and combine it with data from the Cassini probe that spectacularly dived through these rings last year, to understand how quickly this process is playing out.
The team found the rings are shedding an astonishing amount of material, raining anywhere between 432 and 2,870 kg (950 and 6,300 lb) down on the planet every second.
"We estimate that this 'ring rain' drains an amount of water products that could fill an Olympic-sized swimming pool from Saturn's rings in half an hour," said James O'Donoghue of NASA's Goddard Space Flight Center in Greenbelt, Maryland. "From this alone, the entire ring system will be gone in 300 million years, but add to this the Cassini-spacecraft measured ring-material detected falling into Saturn's equator, and the rings have less than 100 million years to live. This is relatively short, compared to Saturn's age of over 4 billion years."
The rates of icy rainfall also shed further light on the age of Saturn's rings, as it offers an indication as to how long it took for the C-ring, which sits inside the much denser B-ring, to look as it does today. According to the scientists, the data suggests that the rings were formed much later in Saturn's life, and are probably no more than 100 million years old.
"We are lucky to be around to see Saturn's ring system, which appears to be in the middle of its lifetime," says O'Donoghue. "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!"
The scientists have published their research in the journal Icarus, while you can find out more in the video below.