As far as planets go, they don’t get much more iconic than Saturn: a huge golden ball encircled by gigantic rings.
There’s nothing else quite like it in the Solar System.
Right now, it’s hard to see Saturn in the sky. It appears close to the Sun, so only visible just before sunrise.But if you did manage to check out Saturn through a backyard telescope, you’d see a yellowish orb, perhaps a few moons — but no rings.
It seems like they’ve vanished.
So why are Saturn’s famous rings currently invisible, and when will they reappear?
Where did Saturn’s rings come from?
Astronomers have been fascinated by Saturn’s magnificent rings since Galileo peered through his telescope in 1610 and spotted bulges either side of the planet.
He suspected they were moons but wasn’t sure.
Nearly 50 years later, Dutch mathematician and physicist Christiaan Huygens announced those bulges were, in fact, rings.
Since then, better telescopes and space missions have provided a wealth of information about the rings.There are seven “groups” of rings, labelled A to G in the order they were discovered, Laura Driessen, an astronomer at University of Sydney, says.
“The rings are mostly made out of water ice, and these bits of ice can be from a grain of sand in size up to the size of a mountain.
“There is also some dust and little bits of rock in these rings.”
Astronomers know where at least one ring came from. The diffuse outer E-ring comprises icy particles from the Saturnian moon Enceladus, perhaps sprayed from the moon’s south pole.Exactly how the other rings formed is a mystery, but one theory is that sometime in the past, a moon or large comet got too close to Saturn and was ripped apart by its gravity.
As to when this happened is also a mystery. Some estimates put the rings’ age at around 200 million years old, while others suggest they’re much older — closer to 4 billion years.
Then, over millions of years, Saturn’s rotation herded those moon or comet bits into the rings we see today.
“You can imagine it’s like water going down the drain. You end up with a flat whirlpool,” Dr Driessen says.
And the rings are extremely flat. They can be as little as 10 metres thick, but extend 280,000 kilometres into space.
Why have Saturn’s rings ‘vanished’?
Saturn’s rings’ vanishing act comes down to the fact that the gas giant is tilted on its axis by 26.7 degrees, similar to Earth’s tilt of 23.5 degrees.
