which planets are made of gas

All four of the outer planets in our solar system are mostly made of gas:

• Jupiter – primarily hydrogen and helium; the largest planet and a classic gas giant.

• Saturn – also mainly hydrogen and helium, another well-known gas giant with its famous rings.

• Uranus – has a thick atmosphere rich in hydrogen, helium, and methane, but is usually classified as an ice giant because of its large amount of “icy” materials like water, ammonia, and methane deep inside.

• Neptune – similar to Uranus, with a hydrogen–helium–methane atmosphere and an icy interior, so it is also classed as an ice giant rather than a pure gas giant.

So, if you’re asking “which planets are made of gas,” the simple answer is: Jupiter, Saturn, Uranus, and Neptune are the gas-dominated planets, but only Jupiter and Saturn are strictly called gas giants, while Uranus and Neptune are ice giants.