List of planet types

From top to bottom: Mercury, Venus without its atmosphere, Earth and the Moon, Mars, Jupiter, Saturn, Uranus, and Neptune. (Not to scale)

The following is a list of planet types:

List

Artist's impression of COROT-7b, likely a lava exoplanet.

Descriptions and tables

By mass regime

Planet type Description
Giant planet A massive planet. They are most commonly composed primarily of 'gas' (hydrogen and helium) or 'ices' (volatiles such as water, methane, and ammonia), but may also be composed primarily of rock. Regardless of their bulk compositions, giant planets normally have thick atmospheres of hydrogen and helium.
Mesoplanet Mesoplanets are planetary bodies with sizes smaller than Mercury but larger than Ceres. The term was coined by Isaac Asimov. Assuming "size" is defined by linear dimension (or by volume), mesoplanets should be approximately 1,000 km to 5,000 km in diameter.
Mini-Neptune A mini-Neptune (sometimes known as a gas dwarf or transitional planet) is a planet smaller than Uranus and Neptune, up to 10 Earth masses. Those planets have thick hydrogen–helium atmospheres, probably with deep layers of ice, rock or liquid oceans (made of water, ammonia, a mixture of both, or heavier volatiles).
Planemo Planetary-mass object, an object which is hydrostatically round due to self-gravitation, but whose mass is insufficient to initiate fusion at its core to become a star.
Planetar either a brown dwarf—an object with a size larger than a planet but smaller than a star—that has formed by processes that typically yield planets; or a sub-brown dwarf, —an object smaller than a brown dwarf that does not orbit a star.
Super-Earth A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below the mass of the Solar System's smaller gas giants Uranus and Neptune, which are 15 and 17 Earth masses respectively.
Super-Jupiter A super-Jupiter is an astronomical object that's more massive than the planet Jupiter.
Sub-Earth Sub-Earth is a classification of planets "substantially less massive" than Earth and Venus.

By orbital regime

Planet type Description
Circumbinary planet An exoplanet that orbits two stars.
Double planet
(Binary planet) 		Two planetary-mass objects orbiting each other.
Dwarf planet A planetary-mass object that orbits its star, which does not represent an overwhelming proportion of the mass in its orbital zone and does not control the orbital parameters of those objects (antonym: major planet)
Eccentric Jupiter A gas giant that orbits its star in an eccentric orbit.
Exoplanet A planet that does not orbit the Sun, but a different star, a stellar remnant, or a brown dwarf.
Extragalactic planet An exoplanet outside the Milky Way.
Goldilocks planet A Goldilocks planet is a planet that falls within a star's habitable zone. The name comes from the children's fairy tale of Goldilocks and the Three Bears, in which a little girl chooses from sets of three items, ignoring the ones that are too extreme (large or small, hot or cold, etc.), and settling on the one in the middle, which is "just right".
Hot Jupiter Hot Jupiters are a class of extrasolar planets whose characteristics are similar to Jupiter, but that have high surface temperatures because they orbit very close—between approximately 0.015 and 0.5 astronomical units (2.2×106 and 74.8×106 km)—to their parent stars, whereas Jupiter orbits its parent star (the Sun) at 5.2 astronomical units (780×106 km), causing low surface temperatures.
Hot Neptune A hot Neptune is an extrasolar planet in an orbit close to its star (normally less than one astronomical unit away), with a mass similar to that of Uranus or Neptune.
Inferior planets The planets whose orbits lie within the orbit of Earth.[NB 1]
Inner planet The inner planets are those planets in the Solar System that have orbits smaller than the asteroid belt.[NB 2]
Major planet Planetary-mass objects which orbit stars that dominate their orbital zone and comprise the vast majority of the mass in that zone (antonym: dwarf planet)
Outer planet The outer planets are those planets in the Solar System beyond the asteroid belt, and hence refers to the gas giants.
Pulsar planet Pulsar planets are planets that are found orbiting pulsars, or rapidly rotating neutron stars.
Rogue planet
(Interstellar planet) 		A rogue planet is a planetary-mass object that orbits the galaxy directly.
Superior planets The planets whose orbits lie outside the orbit of Earth.[NB 1]
Trojan planet The discovery of a pair of co-orbital exoplanets has been reported but later retracted.One possibility for the habitable zone is a trojan planet of a gas giant close to its star.

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 type of terrestrial planet that could form if protoplanetary discs are carbon-rich and oxygen-poor.
Coreless planet A theoretical type of planet that has undergone planetary differentiation but has no metallic core. It is not the same as a hollow Earth.
Desert planet A theoretical type of 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 helium planet is a theoretical type of 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 An ice giant is a giant planet composed mainly of 'ices'—volatile substances heavier than hydrogen and helium, such as water, methane, and ammonia—as opposed to 'gas' (hydrogen and helium).
Ice planet An ice planet is a type of planet with an icy surface. Ice planets consist of a global cryosphere. Ice planets are bigger versions of Solar System's icy moons such as Europa, Enceladus, and Triton, dwarf planets Pluto and Eris, and many other icy Solar System bodies.
Iron planet An iron planet is a type of planet that consists primarily of an iron-rich core with little or no mantle.
Lava planet A lava planet is a hypothetical type of terrestrial planet, with a surface mostly or entirely covered by molten lava. Situations where such planets could exist include a young terrestrial planet just after its formation, a planet that has recently suffered a large collision event, or a planet orbiting very close to its star, causing intense irradiation and tidal forces.
Ocean planet An ocean planet (also termed a waterworld) is a hypothetical type of planet which has a substantial fraction of its mass made of water.
Protoplanet Protoplanets are large planetary embryos that originate within protoplanetary discs and have undergone internal melting to produce differentiated interiors. They are believed to form out of kilometer-sized planetesimals that attract each other gravitationally and collide.
Puffy planet Gas giants with a large radius and very low density are sometimes called "puffy planets" or "hot Saturns", due to their density similar to Saturn's.
Silicate planet A terrestrial planet that is composed primarily of silicate rocks.
Terrestrial planet A terrestrial planet, telluric planet or rocky planet is a planet that is composed primarily of carbonaceous or silicate rocks or metals.

Other

Planet type Description
Earth analog A planet with environmental conditions similar to those found on Earth.
Hypothetical planet A hypothetical planet or hypothetical planetary object is a planet or similar body whose existence is not proven, but is believed by some to exist.
Classical planets The planets as known by the ancients, the Moon, the Sun, Mercury, Venus, Mars, Jupiter, Saturn

In fiction

Imaged bodies

Bodies imaged up close of various types:

Solar System
Sun
(star)		 Jupiter
(planet)		 Saturn
(planet)		 Uranus
(planet)		 Neptune
(planet)		 Earth
(planet)		 Venus
(planet)
Mars
(planet)		 Ganymede
(moon of Jupiter)		 Titan
(moon of Saturn)		 Mercury
(planet)		 Callisto
(moon of Jupiter)		 Io
(moon of Jupiter)		 Moon
(moon of Earth)
Europa
(moon of Jupiter)		 Triton
(moon of Neptune)		 Pluto
(Kuiper belt object)		 Titania
(moon of Uranus)		 Rhea
(moon of Saturn)		 Oberon
(moon of Uranus)		 Iapetus
(moon of Saturn)
Charon
(moon of Pluto)		 Umbriel
(moon of Uranus)		 Ariel
(moon of Uranus)		 Dione
(moon of Saturn)		 Tethys
(moon of Saturn)		 Ceres
(belt asteroid)		 Vesta
(belt asteroid)
Enceladus
(moon of Saturn)		 Miranda
(moon of Uranus)		 Proteus
(moon of Neptune)		 Mimas
(moon of Saturn)		 Hyperion
(moon of Saturn)		 Phoebe
(moon of Saturn)		 Janus
(moon of Saturn)
Amalthea
(moon of Jupiter)		 Epimetheus
(moon of Saturn)		 Thebe
(moon of Jupiter)		 Lutetia
(belt asteroid)		 Prometheus
(moon of Saturn)		 Pandora
(moon of Saturn)		 Mathilde
(belt asteroid)
Hydra
(moon of Pluto)		 Helene
(moon of Saturn)		 Nix
(moon of Pluto)		 Ida
(belt asteroid)		 Atlas
(moon of Saturn)		 Telesto
(moon of Saturn)		 Calypso
(moon of Saturn)
Phobos
(moon of Mars)		 Eros
(near-Earth asteroid)		 Deimos
(moon of Mars)		 Gaspra
(belt asteroid)		 Tempel 1
(comet)		 Šteins
(belt asteroid)		 Borrelly
(comet)
Churyumov–
Gerasimenko
(comet)		 Wild 2
(comet)		 Methone
(moon of Saturn)		 Hartley 2
(comet)		 Dactyl
(moon of Ida)
Closely imaged object with only non-free images: Toutatis, Itokawa
Objects imaged only at low resolution: Halley's Comet, Styx, Kerberos, Braille, Annefrank, Nereid, and Larissa; see also radar-imaged NEOs

See also

Notes

The terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate as 'inferior' those planets (Mercury and Venus) whose epicycle remained collinear with Earth and the Sun, compared to the 'superior' planets (Mars, Jupiter, and Saturn) that did not.</ref>; -webkit-column-width: [NB 1]; column-width: [NB 1]; list-style-type: decimal;">
  1. 1 2 3 4 The terms "inferior planet" and "superior planet" were originally used in the geocentric cosmology of Claudius Ptolemy to differentiate as 'inferior' those planets (Mercury and Venus) whose epicycle remained collinear with Earth and the Sun, compared to the 'superior' planets (Mars, Jupiter, and Saturn) that did not.
  2. ↑ The four inner or terrestrial planets have dense, rocky compositions, few or no moons, and no ring systems. They are composed largely of refractory minerals, such as the silicates, which form their crusts and mantles, and metals, such as iron and nickel, which form their cores. Three of the four inner planets (Venus, Earth and Mars) have atmospheres substantial enough to generate weather; all have impact craters and tectonic surface features, such as rift valleys and volcanos. The term inner planet should not be confused with inferior planet, which designates those planets that are closer to the Sun than Earth is (i.e. Mercury and Venus).

External links

References

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