Saturn has the lowest density of all the planets in the Solar System. The actual number is 0.687 grams per cubic centimeter. This is actually less dense than water; if you had a large enough pool of water, Saturn would float.

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

Just for comparison, Jupiter has an average density of 1.33 grams per cubic centimeter. So it wouldn’t float on water. And Earth, the densest planet in the Solar System, measures 5.51 grams/cubic centimeter.

If you’d like to calculate the density of Saturn for yourself, grab a calculator, and then divide the mass of Saturn (5.6846Ã—1026 kg) by its volume (8.2713Ã—1014 cubic kilometers. This gives you a final number of 0.687 g/cubic centimeter.

Here’s an article about a fluffy extrasolar planet, even less dense than Saturn, and more information about the density of Jupiter.

Here’s a textbook that helps you make the density calculations for yourself, and more information here.

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.