Saturn is clearly shows in the skies now, a beautiful ringed world with a thickness so short it would float in water. Wait. No. That's in reality wrong, says science blogger Rhett Allain.

You are watching: Saturn is less dense than water


Not the ideal image - but I take it this with my phone looking through my telescope. Saturn can easily be seen with a quite pair of binoculars.

Is there a cooler object in the skies than Saturn? maybe Jupiter, however I prefer Saturn a little better. If you understand what you are looking for, you deserve to see the ring of Saturn also with a pair of binoculars. Personally, ns love getting out the telescope and also showing Saturn come people. Your expressions when they view it display their amazement. Most human being don't realize the you have the right to ACTUALLY see the rings.

Enough around viewing Saturn. Here is the one point that bothers me. Girlfriend will often see in textbooks and also other media that Saturn has a low density and would actually float in water. No. This is wrong. Well, it's sort of wrong.

The density of Saturn

Let's assume that Saturn is a sphere. Us can conveniently calculate the density now. Well, conveniently assuming that we look up worths for the radius and also the mass. Follow to Wikipedia, Saturn has actually a mass of 5.68 x 1026 kg and a radius of about 5.6 x 107 meters. Understanding the volume that a sphere, we acquire the following calculation because that the density.


The thickness of water is 1000 kg/m3. What walk this mean? Well, if I have a block the some product underwater then ns can attract the following two pressures on it:


On the surface of the Earth, the magnitude of the gravitational force can be composed as:


Here I just wrote the mass of the object as the product that the thickness of the object (ρo) and the volume that the thing (Vo). For the buoyancy force, I have the right to calculate this as the weight of the water displaced. This would certainly be created as:


Both the weight and the buoyancy force have the exact same Vog term. The just thing the is various is the density. So, if the density of water is greater than the density of the object, the buoyancy pressure when the thing is fully submerged will certainly be better than the weight. In order come be in ~ equilibrium, the object would certainly be just partially submerged. We generally call this "floating". And also here you watch that if the thickness of an item is less than the density of water, that object will certainly float.

If you desire a much more detailed source of the buoyancy pressure - examine out this post about the Magdeburg Water Bridge.

Would Saturn Float?

Saturn's density is much less than water. Things with a density less 보다 water to rise - things prefer ducks, tiny rocks and also gravy. Therefore it appears logical the Saturn would likewise float. Right? Wrong.

See more: How Far Is Yuba City From Sacramento, Ca, How To Get From Sacramento To Yuba City

How much water would certainly you need for Saturn come float? Let's i think for currently that this is some ginormous earth with as much water as we need. Also, I will assume the in this region of water, the gravitational ar is consistent and pointing straight down because the world is therefore large.

If the planet might float (see below), just how deep would certainly the water must be? because that a floating object, the buoyancy force is equal to the gravitational force. This method that only part of the earth would be underwater. But how much? If I contact the volume of the planet underwater Vd (d is because that displacement), then I can write: