How Old is Saturn?

Article written: 3 Jul , 2008
Updated: 24 Dec , 2015
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Saturn formed with the rest of the planets 4.6 billion years ago, out of a spinning disk of gas and dust. This dust collapsed down to form the Sun, and planets formed out of the disk around it. This is why all of the planets orbit the Sun in the same direction.

That’s the easy question.

You can also check out these cool telescopes that will help you see the beauty of planet Saturn.

The more complicated question is, how old are Saturn’s rings? Some parts might be almost as old as the Solar System, but others are being continuously refreshed. The primary theory for the formation of Saturn’s Rings is that a 300 km moon was torn apart by Saturn’s gravity into the ring system that we see today. But that probably happened more than 4 billion years old.

But Saturn’s rings are bright, and almost made of pure water ice. Since infalling dust should have darkened the rings, they might be as young as 100 million years old. Or perhaps they are ancient, but regular collisions between ring objects keep them looking fresh and new.

One interesting note. Astronomers think that the composition of Saturn – 88% hydrogen and 11% helium with other trace elements – almost exactly matches the composition of the early solar nebula. Saturn is like a miniature version of the Solar System.

Here’s an article from Universe Today that discusses how Saturn’s rings could be as old as the Solar System, and another article about how gas giant planets might have consumed many of their moons early on in their history.

Ask an Astronomer has another answer to this question, and another look at the age of the rings from Geology.com.

We have recorded two episodes of Astronomy Cast just about Saturn. The first is Episode 59: Saturn, and the second is Episode 61: Saturn’s Moons.


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