Natural satellite

moonmoonssatellitesatellitesnatural satellitesnaturalplanetary mooncompanionConcomitantindirectly
A natural satellite, or moon, is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).wikipedia
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Astronomical object

celestial bodiescelestial bodycelestial object
A natural satellite, or moon, is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
Examples of astronomical objects include planetary systems, star clusters, nebulae, and galaxies, while asteroids, moons, planets, and stars are astronomical bodies.

Orbit

orbitsorbital motionplanetary motion
A natural satellite, or moon, is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
In physics, an orbit is the gravitationally curved trajectory of an object, such as the trajectory of a planet around a star or a natural satellite around a planet.

Solar System

outer Solar Systeminner Solar Systemouter planets
In the Solar System there are six planetary satellite systems containing 205 known natural satellites. Every natural celestial body with an identified orbit around a planet of the Solar System, some as small as a kilometer across, has been considered a moon, though objects a tenth that size within Saturn's rings, which have not been directly observed, have been called moonlets.
Of the objects that orbit the Sun indirectly—the moons—two are larger than the smallest planet, Mercury.

Satellite system (astronomy)

satellite systemring of satellitessatellite systems
In the Solar System there are six planetary satellite systems containing 205 known natural satellites.
Generally speaking, it is a set of natural satellites (moons), although such systems may also consist of bodies such as circumplanetary disks, ring systems, moonlets, minor-planet moons and artificial satellites any of which may themselves have satellite systems of their own.

Dwarf planet

dwarf planetsList of dwarf planetsplanet
Four IAU-listed dwarf planets are also known to have natural satellites: Pluto, Haumea, Makemake, and Eris. Triton is another exception; although large and in a close, circular orbit, its motion is retrograde and it is thought to be a captured dwarf planet.
A dwarf planet is a planetary-mass object that does not dominate its region of space (as a true planet does) and is not a satellite.

Moons of Pluto

moons5natural satellite of Pluto
Four IAU-listed dwarf planets are also known to have natural satellites: Pluto, Haumea, Makemake, and Eris.
The dwarf planet Pluto has five moons down to a detection limit of about 1 km in diameter.

Moon

lunarthe MoonLuna
The first known natural satellite was the Moon, but it was considered a "planet" until Copernicus' introduction of De revolutionibus orbium coelestium in 1543.
The Moon is an astronomical body that orbits the Earth as its only permanent natural satellite.

Small Solar System body

small Solar System bodiessmall bodiesmacroscopic system
A natural satellite, or moon, is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
A small Solar System body (SSSB) is an object in the Solar System that is neither a planet, a dwarf planet, nor a natural satellite.

Makemake

136472 Makemake2005 FY 9 Make- make
Four IAU-listed dwarf planets are also known to have natural satellites: Pluto, Haumea, Makemake, and Eris.
Makemake has one known satellite, S/2015 (136472) 1.

Moons of Haumea

2Haumea's moonsmoons
Four IAU-listed dwarf planets are also known to have natural satellites: Pluto, Haumea, Makemake, and Eris.
The outer Solar System dwarf planet Haumea has two known moons, Hiʻiaka and Namaka, named after Hawaiian goddesses.

Planet

planetsFormer classification of planetsplanemo
A natural satellite, or moon, is, in the most common usage, an astronomical body that orbits a planet or minor planet (or sometimes another small Solar System body).
Six of the planets are orbited by one or more natural satellites.

Eris (dwarf planet)

Eris136199 Eris2003 UB313
Four IAU-listed dwarf planets are also known to have natural satellites: Pluto, Haumea, Makemake, and Eris.
It has one known moon, Dysnomia.

Moonlet

tiny moons
Every natural celestial body with an identified orbit around a planet of the Solar System, some as small as a kilometer across, has been considered a moon, though objects a tenth that size within Saturn's rings, which have not been directly observed, have been called moonlets.
A moonlet, minor moon, minor natural satellite, or minor satellite is a particularly small natural satellite orbiting a planet, dwarf planet, or other minor planet.

Irregular moon

irregular satelliteirregularirregular satellites
In contrast, irregular satellites (generally orbiting on distant, inclined, eccentric and/or retrograde orbits) are thought to be captured asteroids possibly further fragmented by collisions.
In astronomy, an irregular moon, irregular satellite or irregular natural satellite is a natural satellite following a distant, inclined, and often eccentric and retrograde orbit.

Regular moon

regular satelliteregular satellitesregular
The natural satellites orbiting relatively close to the planet on prograde, uninclined circular orbits (regular satellites) are generally thought to have been formed out of the same collapsing region of the protoplanetary disk that created its primary.
In astronomy, a regular moon is a natural satellite following a relatively close and prograde orbit with little orbital inclination or eccentricity.

Triton (moon)

TritonAndvari Triton
Triton is another exception; although large and in a close, circular orbit, its motion is retrograde and it is thought to be a captured dwarf planet.
Triton is the largest natural satellite of the planet Neptune, and the first Neptunian moon to be discovered.

Minor-planet moon

moonasteroid moonbinary
, there are 334 other minor planets known to have moons.
A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite.

Earth

Earth's surfaceterrestrialworld
The only observed example is, which was a temporary satellite of Earth for nine months in 2006 and 2007.
Earth's gravity interacts with other objects in space, especially the Sun and the Moon, which is Earth's only natural satellite.

Titan (moon)

TitanSaturn's moon Titanatmosphere
The only known exception is Saturn's natural satellite Hyperion, which rotates chaotically because of the gravitational influence of Titan.
It is the only moon known to have a dense atmosphere, and the only known body in space, other than Earth, where clear evidence of stable bodies of surface liquid has been found.

Nereid (moon)

NereidNereids
For example, Jupiter's Himalia, Saturn's Phoebe, and Neptune's Nereid have rotation periods in the range of ten hours, whereas their orbital periods are hundreds of days.
Nereid is the third-largest moon of Neptune.

Temporary satellite

Temporarily captured orbitertemporary orbit
According to simulations, temporary satellites should be a common phenomenon.
A temporary satellite is an asteroid which has been captured by the gravitational field of a planet and thus became the planet's natural satellite, but, unlike irregular moons of the larger outer planets of the Solar System, will later leave its orbit around the planet.

Subsatellite

Moonmoonlesser moon
No "moons of moons" or subsatellites (natural satellites that orbit a natural satellite of a planet) are currently known.
A subsatellite is a natural or artificial satellite that orbits a natural satellite, i.e. a "moon of a moon".

Himalia (moon)

HimaliaJupiter VI
For example, Jupiter's Himalia, Saturn's Phoebe, and Neptune's Nereid have rotation periods in the range of ten hours, whereas their orbital periods are hundreds of days.
Himalia (Jupiter VI) is the largest irregular satellite of Jupiter, with an estimated diameter of at least 205 km.

Iapetus (moon)

Iapetus IapetusEquatorial ridge
It has also been proposed that Saturn's moon Iapetus had a satellite in the past; this is one of several hypotheses that have been put forward to account for its equatorial ridge.
Iapetus, or occasionally Japetus, is the third-largest natural satellite of Saturn, eleventh-largest in the Solar System, and the largest body in the Solar System known not to be in hydrostatic equilibrium.

Retrograde and prograde motion

retrogradeprograderetrograde orbit
In contrast, irregular satellites (generally orbiting on distant, inclined, eccentric and/or retrograde orbits) are thought to be captured asteroids possibly further fragmented by collisions. The natural satellites orbiting relatively close to the planet on prograde, uninclined circular orbits (regular satellites) are generally thought to have been formed out of the same collapsing region of the protoplanetary disk that created its primary.
Most natural satellites have prograde orbits about their planets.