List of planet types
The following is a list of planet types by their mass, orbit, physical and chemical composition, or by another classification.
The IAU defines that a planet in the Solar System must orbit around the Sun, has enough mass to assume hydrostatic equilibrium, and has "cleared its neighborhood". There is currently no accepted definition for exoplanets.
Under the IAU definition, true or "major planets" can be distinguished from other planetary-mass objects, such as dwarf planets and sub-brown dwarfs. Nonetheless, certain planet types have been applied to other planetary-mass objects; the Pluto–Charon system has been referred to as "double dwarf planets", for instance.
By mass regime
By orbital regime
By composition
| Planet type | Description |
| Chthonian planet | An extrasolar planet that orbits close to its parent star. Most Chthonian planets are expected to be gas giants that had their atmospheres stripped away, leaving their cores. |
| Carbon planet | A theoretical terrestrial planet that could form if protoplanetary discs are carbon-rich and oxygen-poor. |
| Coreless planet | A theoretical planet that has undergone planetary differentiation but has no metallic core. Not to be confused with the Hollow Earth concept. |
| Desert planet | A theoretical terrestrial planet with very little water. |
| Gas dwarf | A low-mass planet composed primarily of hydrogen and helium. |
| Gas giant | A massive planet composed primarily of hydrogen and helium. |
| Helium planet | A theoretical planet that may form via mass loss from a low-mass white dwarf. Helium planets are predicted to have roughly the same diameter as hydrogen–helium planets of the same mass. |
| Ice giant | A giant planet composed mainly of 'ices'—volatile substances heavier than hydrogen and helium, such as water, methane, and ammonia—as opposed to 'gas'. |
| Ice planet | A theoretical planet with an icy surface and consists of a global cryosphere. |
| Iron planet | A theoretical planet that consists primarily of an iron-rich core with little or no mantle. |
| Lava planet | A theoretical terrestrial planet with a surface mostly or entirely covered by molten lava. |
| Ocean planet | A theoretical planet which has a substantial fraction of its mass made of water. |
| Protoplanet | A large planetary embryo that originates within protoplanetary discs and has undergone internal melting to produce differentiated interiors. Protoplanets are believed to form out of kilometer-sized planetesimals that attract each other gravitationally and collide. |
| Puffy planet | Also known as a hot Saturn. A gas giant with a large radius and very low density which is similar to or lower than Saturn's. |
| Silicate planet | A terrestrial planet that is composed primarily of silicate rocks. All four inner planets in our Solar System are silicon-based. |
| Terrestrial planet | Also known as a telluric planet or rocky planet. A planet that is composed primarily of carbonaceous or silicate rocks or metals. |