Ice giant in mass. In 1952, science fiction writer James Blish coined the term "gas giant" and it was used to refer to the large non-terrestrial planets of the Solar System. However, in the 1990s, the compositions of Uranus and Neptune were discovered to be significantly different from those of Jupiter and Saturn. They are primarily composed of elements heavier than hydrogen and helium, constituting a separate type of giant planet altogether. Because during their formation Uranus and Neptune incorporated their material as either ices or gas trapped in water ice, the term "ice giant" came into use. Modelling the formation of
Planetary system transfer to another star, creating new protoplanetary disks and second- and third-generation planets which may differ in composition from the original planets which may also be affected by the mass transfer. The Solar System consists of an inner region of small rocky planets and outer region of large gas giants. However, other planetary systems can have quite different architectures. Studies suggest that architectures of planetary systems are dependent on the conditions of their initial formation. Many systems with a hot Jupiter gas giant very close to the star have been found. Theories, such as planetary migration or scattering, have been