* Gas giants are massive. Planets like Jupiter and Saturn are made mostly of hydrogen and helium, but they have *so much* of it that the immense gravity compresses the gas at their core.
* Pressure turns gas into liquid. The pressure at the core of these planets is incredibly high, like billions of times the pressure at Earth's surface. This pressure is so intense that it forces the hydrogen and helium to become liquid, even though they'd be gases under normal conditions.
* The core is still a mystery. We're not completely sure what the deep core of gas giants is like. Some scientists believe it could even be solid, made of rock and ice.
So, while gas giants are mostly made of gas, they don't just float around like bubbles. The immense pressure at their cores makes them dense and gives them a solid-like structure.
Think of it this way: Imagine squeezing a balloon. The more you squeeze, the denser the air inside becomes. Gas giants are like extremely squeezed balloons – their gravity acts as the squeezing force.
