Curious Kids: why does Saturn have rings?
- Written by Lucyna Kedziora-Chudczer, Program Manager / Adjunct Research Fellow, Swinburne University of Technology
If you have a question you’d like an expert to answer, send it to curiouskids@theconversation.edu.au.
Why does Saturn have rings? – Isla, age 7, Killarney.
Most people think many millions of years ago, Saturn didn’t have rings at all. Instead, it had a big moon moving around it.
Eventually, this moon came very close to Saturn while moving faster and faster around it.
This caused the moon to get pulled in two directions at once. It burst and broke into pieces that eventually spread around the planet into a flattened doughnut shape made of ice and rock.
The chunks kept smashing into each other, which made a lot of powdery dust and snow. Some chunks fell onto Saturn or floated off into space. That’s still happening today, and in the distant future the rings will disappear entirely.
Pieces of ice and rock spread around the planet into a flattened doughnut.
Shutterstock
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Discovering Saturn’s rings
We didn’t always know Saturn had rings.
Here is a close up photo of Saturn’s rings.
JPL/NASA
A few hundred years ago, an astronomer named Galileo looked at the sky through one of the first telescopes. When he used it to look at Saturn, he thought the planet looked a bit like the head of a teddy bear with two big ears. He thought it may be made of three planets.
Years later, astronomers used better telescopes and realised Saturn was surrounded by what looked like a large flat disk.
At first, astronomers thought the disk might actually touch Saturn. An astronomer named Christiaan Huygens thought the disk around Saturn was as solid as a pancake or a ring on a finger.
Another astronomer, Giovanni Cassini, was first to notice the ring had some gaps in it.
Now we know the rings are made of moon dust and rocks. And because Saturn is very far away from the Sun, it is a very cold planet. That means the rocks in Saturn’s rings are very icy. Some are even made entirely of ice, like snowballs.
Saturn’s rings are very bright because snow reflects sunlight strongly.
When people sent spaceships to other planets and took close-up photos, they discovered Jupiter, Uranus and Neptune also have rings. But these rings are very faint and hard to see from Earth. They also realised these planets have many moons – some smaller and some bigger than Earth’s Moon.
Thank you and goodbye, Cassini
If you are interested to learn more about Saturn and its beautiful rings, you might like to read about the Cassini–Huygens space research mission. It involved sending a spaceship (with no people on it) to Saturn.
It took about seven years for Cassini to get to Saturn. Then, for about 10 years, Cassini sent photographs and data back to Earth so we could learn as much as we could about Saturn before the spacecraft ran out of fuel. At the end of the mission, on Friday, September 15, 2017, Cassini dived into Saturn’s atmosphere.
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