Saturn Floats! But What if a Sea Was Found Large Enough to Sail It On?

Saturn Floats! But What if a Sea Was Found Large Enough to Sail It On?

Saturn is the only planet less dense than water, so it would float if a sea could be found large enough to put it in.

Saturn floating on the sea

So how dense is Saturn and what makes it like that?


To start off we need to know the density of water. This is measured as 1 g/cm3. Although this value isn’t quite true as water will change its density depending on the temperature of the water.  So this is really a rounded up figure.  The range of difference isn’t that great though, being about 0.96 g/cm3 at 100 0C and 0.99 g/cm3 at 4 0C when it is at its densest. On a side note water is a fascinating substance as it becomes less dense when it freezes to ice. Hence, ice floats on the top of seas and oceans so they never totally freeze up. If this didn’t happen it would mean the end of life on the planet. So life as we know it is dependent on this chemical strangeness of water.


Now Saturn’s average density is way below that of water at around 0.687 g/cm3. This is about one-eighth of the density of planet Earth and around 30% less dense than water. Being less dense than water means that it would float on an ocean big enough to contain it.


Saturn is the only planet in the Solar System that is less dense than water. So what gives it this property?


Saturn’s core is probably made from rock, nickel and iron. Now all of these would sink rapidly if you put them into water. It is the outer layers of Hydrogen and Helium that make the average density of Saturn less than water. Now this conjures up a really nice thought experiment. Some people argue that you would need to remove the dense core for this to be true fact, but others say it would float regardless. 

Ocean planet by lucianomendez

Artist’s impression of an ocean planet by: Lucianomendez

The other argument against this fact, which I really enjoy, is that the ocean would need to be so large that it would collapse under its own gravity to form a spherical planet itself and if Saturn were ever to come close to a planet of water of this size the gravity of the water world would squash Saturn flat. Hence, Saturn would never actually be able to float on the ocean it would become part of it, crushed by the gravity.


Whatever the outcome just imagine the ring it would leave in the bath.

If you would like to see Saturn, have a look at this article on how to view the planets.

Find more on: Astronomy Science and News

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