the.com/gas giant
a planet so big it never bothered growing a solid floor.
means a large planet made mostly of hydrogen and helium with no solid surface, just gas and pressure all the way down.
from coined by sci-fi writer james blish in 1952, who needed a term for jupiter-like worlds after realizing planet already meant something specific to astronomers.
jupiter's corepossibly liquid metallic hydrogen under crushing pressure
density checksaturn would float in a bathtub big enough
no landingyou'd fall forever, gas thickens into liquid gradually
formed earlygrabbed leftover gas before the sun blew it away