Giant planets

Giant planets are sometimes known as gas giants, but many astronomers now apply the term only to Jupiter and Saturn, classifying Uranus and Neptune, which have different compositions, as ice giants. Both names are potentially misleading; the Solar System's giant planets all consist primarily of fluids above their critical points, where distinct gas and liquid phases do not exist. Jupiter and Saturn are principally made of hydrogen and helium, whilst Uranus and Neptune consist of water, ammonia, and methane.