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

Because even tho those planets are made of gas, they’re still absolutely massive. Literally, full of mass, full of stuff.

If you put Uranus/Neptune on a giant hypothetical balance scale, it would take 15-20 earths to equal one of those planets, Jupiter and saturn would take 100+ earths.

They may be mostly gas, but there’s A LOT of gas, they’re just absolutely huge and massive.

Pluto on the other hand is smaller than our own moon. So, for the clarity of classifications, Pluto was reclassified as a Dwarf Planet, because is still a big object, hundreds of miles across, but it really doesn’t fit into the same group as a planet and instead is more similar to other dwarf planets like Ceres or Eris.