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 a semi-major axis of 30.1 astronomical units (au). Typically, ...

(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 "Solar S ...

that

orbit In celestial mechanics, an orbit 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 object or position in space such as a p ...

the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

at a greater distance on average than

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

, 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 long ...

greater than 30.1

astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits t ...

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 (), sometimes called the Öpik–Oort cloud, first described in 1950 by the Dutch astronomer Jan Oort, is a theoretical concept of a cloud of predominantly icy planetesimals proposed to surround the Sun at distances ranging from 2 ...

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) **Most commonly the Main (river) in Germany * Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries ...

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. Its orbit is m ...

s including the ESDOs, EDDOs, and

sednoid A sednoid is a trans-Neptunian object with a perihelion well beyond the Kuiper cliff at . Only four objects are known from this population: 90377 Sedna, , 541132 Leleākūhonua (), and , but it is suspected that there are many more. All four ha ...

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. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

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

centaurs A centaur ( ; grc, κένταυρος, kéntauros; ), or occasionally hippocentaur, is a creature from Greek mythology with the upper body of a human and the lower body and legs of a horse. Centaurs are thought of in many Greek myths as being ...

, 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. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any ellip ...

, 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 S ...

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 lar ...

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 of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...

s by the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

. There are also several

dwarf planet candidate 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 , , , and . Most TNOs have low

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

s typically around 0.09. Their

color Color (American English) or colour (British English) is the visual perceptual property deriving from the spectrum of light interacting with the photoreceptor cells of the eyes. Color categories and physical specifications of color are associ ...

varies from blue-grey to very red (classes BB, BR, IR and RR). The following list also gives an object's full

designation Designation may refer to: * Designation (law), the process of determining an incumbent's successor * Professional certification * Designation (landmarks), an official classification determined by a government agency or historical society * Designa ...

, 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 Plane of reference, reference plane and the orbital plane or Axis of rotation, axis of direction of the orbiting object ...

(''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-center, in geometry * Eccentricity (graph theory) of a v ...

(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" and "List Of Centaurs and Scattered-Disk Objects", completed with remarks and information from Johnston's Archive (diameter,

class Class 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 differentl ...

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

, 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 digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that ...

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 The Outer Solar System Origins Survey (OSSOS) is an astronomical survey and observing program aimed at discovering and tracking trans-Neptunian objects located in the outermost regions of the Solar System beyond the orbit of Neptune. OSSOS is d ...

''
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 is one of the four Carnegie Museums of Pittsburgh, Pennsylvania. It is located in the Chateau neighborhood. It is located across the street from Heinz Field. Overview The Carnegie Science Center is the most visited mu ...

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