noun
Astronomical term for a large planet composed mainly of hydrogen and helium, such as Jupiter or Saturn. Often used in contrast to 岩石惑星 (rocky planets).
See also: 巨大ガス惑星
木星は太陽系最大のガス巨星です。
Jupiter is the largest gas giant in the solar system.
ガス巨星には固体の表面がありません。
Gas giants do not have a solid surface.
Compound of ガス (gas) and 巨星 (giant star/planet). The term is a direct calque from English 'gas giant', used in modern astronomy.