Eli5 how we know that’s gas giants like Jupiter have a very small rock mass while the rest of it is just gas?

Question

How we know if gas giants atmosphere extend to the core while no one was able to check if it true ?

In: Other

Answer 1

Mostly through modeling and the physical properties of gravity and matter.

Jupiter’s mass and size can be reasonably estimated and then its composition can roughly determined.

FWIW from what I know, if you slice Jupiter in half, probably the outer 10% of its radius is mostly hydrogen atmosphere. Diving deeper to the next 20% the pressure is probably high enough to form liquid H, and the remaining 70% the pressure is probably high enough to form solid metallic hydrogen. The center of Jupiter is probably an iron or metal core 10x the size of Earth.