This is a list of

trans-Neptunian objects A trans-Neptunian object (TNO), also written transneptunian object, is any minor planet in the Solar System that orbits the Sun at a greater average distance than Neptune, which has an orbital semi-major axis of 30.1 astronomical units (AU). T ...

(TNOs), which are

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

s in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

that

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

at a greater distance on average than

Neptune Neptune is the eighth and farthest known planet from the Sun. It is the List of Solar System objects by size, fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 t ...

, that is, their orbit has a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the longe ...

greater than 30.1

astronomical unit The astronomical unit (symbol: au or AU) is a unit of length defined to be exactly equal to . Historically, the astronomical unit was conceived as the average Earth-Sun distance (the average of Earth's aphelion and perihelion), before its m ...

s (AU). The

Kuiper belt The Kuiper belt ( ) is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune at 30 astronomical units (AU) to approximately 50 AU from the Sun. It is similar to the asteroid belt, but is far larger—20 times ...

scattered disk The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small Solar System bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc objec ...

, and

Oort cloud The Oort cloud (pronounced or ), sometimes called the Öpik–Oort cloud, is scientific theory, theorized to be a cloud of billions of Volatile (astrogeology), icy planetesimals surrounding the Sun at distances ranging from 2,000 to 200,000 A ...

are three conventional divisions of this volume of space. , the catalog of minor planets contains 901 numbered TNOs. In addition, there are more than 3,000 unnumbered TNOs, which have been observed since 1993. This list consists of all types of TNO subgroups:

classical Kuiper belt object A classical Kuiper belt object, also called a cubewano ( "QB1-o"), is a low-eccentricity Kuiper belt object (KBO) that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axe ...

s, also known as "cubewanos", the

resonant trans-Neptunian object In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object (TNO) in mean-motion orbital resonance with Neptune. The orbital periods of the resonant objects are in a simple integer relations with the period of Neptune, e.g. 1:2, 2 ...

s with their

main Main may refer to: Geography *Main River (disambiguation), multiple rivers with the same name *Ma'in, an ancient kingdom in modern-day Yemen * Main, Iran, a village in Fars Province *Spanish Main, the Caribbean coasts of mainland Spanish territ ...

and higher-order resonant subgroups, the

scattered disc object The scattered disc (or scattered disk) is a distant circumstellar disc in the Solar System that is sparsely populated by icy small Solar System bodies, which are a subset of the broader family of trans-Neptunian objects. The scattered-disc objec ...

s (SDOs), and the

extreme trans-Neptunian object An extreme trans-Neptunian object (ETNO) is a trans-Neptunian object orbiting the Sun well beyond Neptune (30 AU) in the outermost region of the Solar System. An ETNO has a large semi-major axis of at least 150–250 AU. The orbits of ET ...

s including the ESDOs, EDDOs, and

sednoid A sednoid is a trans-Neptunian object with a large semi-major axis and a high perihelion, similar to the orbit of the dwarf planet Sedna. The consensus among astronomers is that there are only four objects that are known from this population: ...

s, which have a semi-major axis of at least 150 AU and a

perihelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

(closest approach to the Sun) greater than that of Neptune. The list also contains several

centaurs A centaur ( ; ; ), occasionally hippocentaur, also called Ixionidae (), is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse that was said to live in the mountains of Thessaly. In one version o ...

, if the object's orbit has a sufficiently large semi-major axis (a). Centaurs have unstable orbits in which the perihelion (q) is well inside of Neptune's orbit but the farthest point (

aphelion An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. The line of apsides (also called apse line, or major axis of the orbit) is the line connecting the two extreme values. Apsides perta ...

, Q) is very distant. The first TNO to be discovered was

Pluto Pluto (minor-planet designation: 134340 Pluto) is a dwarf planet in the Kuiper belt, a ring of Trans-Neptunian object, bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Su ...

in 1930. It became the namesake of a larger group of resonant objects called

plutino In astronomy, the plutinos are a dynamical group of trans-Neptunian objects that orbit in 2:3 mean-motion resonance with Neptune. This means that for every two orbits a plutino makes, Neptune orbits three times. The dwarf planet Pluto is the la ...

s (another such resonant subgroup are the twotinos). It took more than 60 years to discover a second TNO,

Albion Albion is an alternative name for Great Britain. The oldest attestation of the toponym comes from the Greek language. It is sometimes used poetically and generally to refer to the island, but is less common than "Britain" today. The name for Scot ...

( provisionally known as ), in 1992. The largest known trans-Neptunian objects are Pluto and , followed by , , , , , and , all of them being officially recognized as

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit around the Sun, massive enough to be hydrostatic equilibrium, gravitationally rounded, but insufficient to achieve clearing the neighbourhood, orbital dominance like the ...

s by the

IAU The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

except for Gonggong, Sedna, and Orcus. There are also many

possible dwarf planet The number of dwarf planets in the Solar System is unknown. Estimates have run as high as 200 in the Kuiper belt and over 10,000 in the region beyond. However, consideration of the surprisingly low densities of many large trans-Neptunian objects, ...

s, such as ,

Máni Máni (Old Norse: ; "Moon"Orchard (1997:109).) is the Lunar deity, Moon personified in Germanic mythology. Máni, personified, is attested in the ''Poetic Edda'', compiled in the 13th century from earlier traditional sources, and the ''Prose Edd ...

, , , and . Most TNOs have low

albedo Albedo ( ; ) is the fraction of sunlight that is Diffuse reflection, diffusely reflected by a body. It is measured on a scale from 0 (corresponding to a black body that absorbs all incident radiation) to 1 (corresponding to a body that reflects ...

s typically around 0.09. Their

color Color (or colour in English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-our, -or, see spelling differences) is the visual perception based on the electromagnetic spectrum. Though co ...

varies from blue-grey to very red (classes BB, BR, IR and RR). The following list also gives an object's full designation, mean-diameter (D), and discovery circumstances (date, discoverer and discovery site), as well as its orbital

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

(''i'') and

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

(e).

List

This list includes all numbered trans-Neptunian objects with a

greater than 30.1

s (AU), Neptune's average orbital distance from the Sun. The data is sourced from MPC's "List of Trans Neptunian Objects", "List Of Centaurs and Scattered-Disk Objects", and "List of Neptune Trojans", completed with remarks and information from Johnston's Archive (diameter,

class Class, Classes, or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytical concept used d ...

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical op ...

, spectral taxonomy and B–R color index).

Unnumbered TNOs

There are more than 3,000 unnumbered trans-Neptunian objects, defined here as minor planets with a semi-major axis larger than 30.1 AU (Neptune's average orbital distance from the Sun). The data is sourced from MPC's "List of Trans Neptunian Objects" and "List Of Centaurs and Scattered-Disk Objects", completed with information from Johnston's Archive (diameter, class, binary status, etc.). For the list of numbered TNOs, ''see ''.

Trans-Neptunian satellites

A growing number of TNOs are revealed to be

binary systems Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two values (0 and 1) for each digit * Binary function, a function that takes two arguments * Binary operation, a mathematical op ...

with a

minor-planet moon A minor-planet moon is an astronomical object that orbits a minor planet as its natural satellite. , there are 457 minor planets known or suspected to have moons. Discoveries of minor-planet moons (and binary objects, in general) are important ...

orbiting its primary. There are also several multiple systems with more than one satellite.

Diagram: orbital classes

Trans-Neptunian objects colorized by their orbital subclass and plotted in the orbital parameter space (eccentricity and inclination versus semi-major axis). The plot for the entire region contains 1418 objects including plutinos (#185), twotinos (#36), other resonant objects (#124), cubewanos (#420), inner (#40) and outer classical objects (#6), SDOs (#289), sednoids (#11), centaurs (#101) and other TNOs (#206).

Notes

References

External links

How many dwarf planets are there in the outer solar system?
'' Michael Brown'', Caltech
OSSOS TNODB
by the '' Outer Solar System Origins Survey''
Minor Planet Center: List of Transneptunian Objects

* ttp://www.johnstonsarchive.net/astro/tnoslist.html Johnston's Archive: List of Known trans-Neptunian Objects
Johnston's Archive: Trans-Neptunian Objects

Scott Sheppard, ''

Carnegie Science Center The Carnegie Science Center, soon to be The Daniel G. and Carole L. Kamin Science Center, is one of the four Carnegie Museums of Pittsburgh, Pennsylvania. It is located in the Chateau neighborhood. It is located across the street from Acrisure ...

'' {{DEFAULTSORT:List Of Trans-Neptunian Objects Lists of trans-Neptunian objects * Neptunian, trans