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| Compilation of 15 imaged trans-Neptunian objects. The first image compares some of the largest TNOs in terms of size, color and albedo. |
This is a list of trans-Neptunian objects (TNOs), which are minor planets in the Solar System that orbit the Sun at a greater distance on average than Neptune, which means all of their orbits have a semi-major axis greater than 30.1 astronomical units (AU). The Kuiper belt, scattered disk, and Oort cloud are three conventional divisions of this volume of space. [1] [nb 1] As of October 2025 [update] , the catalog of minor planets contains 1,036 numbered TNOs. In addition, there are 4,519 unnumbered TNOs, which have been observed since 1993. [3] [4] [5] [6] [7] [8]
Contents
- List
- Unnumbered TNOs
- Trans-Neptunian satellites
- Diagram: orbital classes
- See also
- Notes
- References
- External links
This list consists of all types of TNO subgroups: classical Kuiper belt objects, also known as "cubewanos", the resonant trans-Neptunian objects with their main and higher-order resonant subgroups, the scattered disc objects (SDOs), and the extreme trans-Neptunian objects including the ESDOs, EDDOs, and sednoids, which have a semi-major axis of at least 150 AU and a perihelion (closest approach to the Sun) greater than that of Neptune. [9] The list also contains several centaurs, 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, Q) is very distant.
The first TNO to be discovered was Pluto in 1930. It became the namesake of a larger group of resonant objects called plutinos (another such resonant subgroup are the twotinos). It took more than 60 years to discover a second TNO, Albion (provisionally known as 1992 QB1), in 1992. The largest known trans-Neptunian objects are Pluto and Eris, followed by Haumea, Makemake, Gonggong, Quaoar, Sedna, and Orcus, all of them being officially recognized as dwarf planets by the IAU except for Gonggong, Sedna, and Orcus. There are also many possible dwarf planets, such as Salacia, Máni, Varda, Ixion, and Varuna. Most TNOs have low albedos typically around 0.09. Their color 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 (i) and eccentricity (e).
