Which class of giant planet is Saturn, like Jupiter?

Saturn is a gas giant, like Jupiter. Both planets are dominated by hydrogen and helium, unlike Uranus and Neptune, which are usually classified as ice giants because heavier compounds make up more of their interiors.

“Gas giant” describes Saturn’s broad planetary composition, not the idea that the whole planet is ordinary gas. Pressure increases enormously with depth, turning hydrogen into dense fluids and eventually metallic hydrogen. Saturn probably has a heavy-element core surrounded by these hydrogen-rich layers, but it has no solid surface for a spacecraft to land on.

Saturn is the Solar System’s sixth planet and second-largest, with an average radius about nine times Earth’s. Its famous rings are mostly water ice, and its yellowish cloud tops contain ammonia crystals. A common mix-up is calling Saturn an ice giant because it is cold and ringed; in astronomy, “ice giant” refers primarily to Uranus and Neptune, not Saturn.