A floating planet? Sure, if you can find an ocean big enough! Charae and Professor B compare the density of Saturn to water and discover that the ringed planet could also be – a life preserving ring!
Listen here [3:00m]:
What’s the facts?
Density – which is the total mass of an object divided by its total volume – is an important measure for planets, telling us what they are made of, even if we can’t actually look inside them. The planets of the Solar System can be roughly sorted into ones made mostly of rock (like Earth), ones made mostly of ice (like Pluto) and ones made mostly of gas (like Saturn). And just as rock is denser than ice, which is denser than gas, the rocky planets are the most dense and gas planets the least dense. In fact, a planet like Saturn, which is mostly made up of the two lightest elements Hydrogen and Helium, has a density that is lower than water, which is conveniently about 1 gram/cubic centimeter. This is despite the fact that Saturn has 95 times more mass than Earth; its mass is just spread out over a very large volume. Earth, by the way, is the densest planet, with a core of solid iron that helps to power a magnetic field that surrounds our planet, keeping us safe from energetic particles from the Sun. So it turns out to be good to live on a dense planet – something to keep in mind when we are searching for other worlds to live on!
Original air date 4 April 2009.