Why is Pluto not considered a planet because it’s too small, but some planets are made entirely of gas and considered planets?

Question

Edit: I know I sound like an idiot in the replies, but I’m really asking genuine questions so thank you all for being patient and answering

In: Physics

Answer 1

Jupiter and the gas giants are made of what we consider gasses, but on the planets they are mostly compressed into liquids by the intense pressure. The gas giants aren’t big clouds you could fly a submarine straight through.