eli5 how gaseous are gas planets?



I learned growing up that gas giants like Saturn and Jupiter are mostly gas. What does that mean exactly? Do they have a ground/crust or is it just gas all the way through?

In: Physics

We don’t know for certain, but basically it starts out as a thin gas at the “surface”, and as you go deeper, it becomes thicker, and if you go deep enough, there’s so much pressure from gravity it condenses into a liquid. So there’s an ocean of hydrogen down there somewhere.

It’s speculated that there *might* be a small rocky core, but it’s mostly just gas: about 90% hydrogen and 10% helium with a tiny amount of other stuff mixed in.

From what little I know… They don’t have a ground/crust the same way the Earth does. As you get deeper and deeper into the planet the pressure increases to monumental levels. It compacts the gas into a liquid like state.

Given the fact they will inevitably been hit by meteors in the past there will be some solid material at the centre. But this is only a small percentage of the planets mass.

They are very gassy, the upper layers are mainly gas, but as you go lower and lower the pressure from all the above gas will eventually become solid/liquid