# List of possible dwarf planets
A possible dwarf planet is a solar-system body that is thought to satisfy the International Astronomical Union's (IAU) definition of a dwarf planet, orbiting the Sun, massive enough for self-gravity to pull it into a nearly round shape, not a satellite, and unable to clear its orbital neighborhood, but that has not yet been officially recognized as one. The IAU has recognized only five dwarf planets: Ceres, Pluto, Haumea, Makemake, and [Eris](https://www.edgepedia.org/eris-dwarf-planet), in order of distance from the Sun.[1](https://science.nasa.gov/dwarf-planets/) Many additional bodies are considered likely to qualify, and estimates of their number range from about ten to several hundred.[2](https://www.livescience.com/space/astronomy/what-are-dwarf-planets-and-how-many-are-there)
| Key fact | Detail |
|---|---|
| Officially recognized | Five: Ceres, Pluto, Haumea, Makemake, and Eris[1](https://science.nasa.gov/dwarf-planets/) |
| Definition (IAU, 2006) | Orbits the Sun, is in hydrostatic equilibrium (nearly round), has not cleared its orbital neighborhood, and is not a satellite[3](https://www.iau.org/IAU/Iau/News/PR2006/iau-2006-general-assembly-resolution-votes.aspx) |
| Approximate size thresholds | A rocky body is expected to become round above roughly 800 km diameter; an icy body above roughly 400 km[4](https://ssd.jpl.nasa.gov/planets/def.html) |
| Widely accepted candidates | Quaoar, Sedna, Orcus, and Gonggong, which many observational astronomers treat as dwarf planets alongside the official five[2](https://www.livescience.com/space/astronomy/what-are-dwarf-planets-and-how-many-are-there) |
| Michael Brown's candidate list | As of November 25, 2025: 10 objects of near-certain dwarf-planet status and 27 more highly likely; an earlier 2011 version listed 390 candidates from "nearly certain" to "possible"[5](https://web.gps.caltech.edu/~mbrown/dps.html) • [6](https://spacemath.gsfc.nasa.gov/Pluto/DwarfPlanetsV3.pdf) |
| Tancredi assessment (2010) | 15 very probable plutoids plus possibly 9 more, drawn from 46 trans-Neptunian objects estimated larger than 450 km[7](https://www.cambridge.org/core/journals/proceedings-of-the-international-astronomical-union/article/physical-and-dynamical-characteristics-of-icy-dwarf-planets-plutoids/5A9DBBF2EB1760433B97CF5A10AD274F) |
| Recent addition | 2017 OF201, announced May 21, 2025: estimated 700 km diameter on an orbit with a semi-major axis of 838 au and a period of about 24,000 years[8](https://arxiv.org/abs/2505.15806) |
| Spacecraft visits | Only two recognized dwarf planets have been visited: Ceres (Dawn, 2015) and Pluto (New Horizons, July 14, 2015)[1](https://science.nasa.gov/dwarf-planets/) |
## The definition and why candidates exist
The IAU introduced the dwarf planet category at its 2006 General Assembly. A planet must orbit the Sun, be nearly round, and have cleared the neighborhood around its orbit; a dwarf planet meets the first two conditions but not the third, and is not a satellite.[3](https://www.iau.org/IAU/Iau/News/PR2006/iau-2006-general-assembly-resolution-votes.aspx) The first members named were [Ceres](https://www.edgepedia.org/ceres-dwarf-planet), Pluto, and 2003 UB313, later named Eris, and the IAU stated at the time that a dozen candidates sat on a "dwarf planet" watchlist that would keep changing as new objects were found and the physics of existing candidates became better known.[3](https://www.iau.org/IAU/Iau/News/PR2006/iau-2006-general-assembly-resolution-votes.aspx)
**Roundness is the physical test.** Self-gravity overcomes material strength and pulls a body into a hydrostatic equilibrium shape only above a size that depends on composition and temperature. The JPL Solar System Dynamics group gives the working figures: a rocky asteroid-like body would be expected to become round if its diameter exceeds about 800 km, while a less dense icy body would be expected to achieve roundness above roughly 400 km.[4](https://ssd.jpl.nasa.gov/planets/def.html) Because no direct size measurement exists for most candidates, classification rests on estimated diameters from thermal emission, stellar occultations, and assumed albedos, together with light-curve shapes that reveal whether the body is ellipsoidal.[7](https://www.cambridge.org/core/journals/proceedings-of-the-international-astronomical-union/article/physical-and-dynamical-characteristics-of-icy-dwarf-planets-plutoids/5A9DBBF2EB1760433B97CF5A10AD274F)
## The official five
Ceres is the only dwarf planet in the inner solar system, orbiting in the main asteroid belt between Mars and Jupiter; it was discovered by Giuseppe Piazzi in 1801 and visited by NASA's Dawn spacecraft, the first dwarf planet ever visited.[1](https://science.nasa.gov/dwarf-planets/) Pluto, discovered in 1930 and reclassified in 2006, is the largest dwarf planet, slightly larger than Eris.[1](https://science.nasa.gov/dwarf-planets/) • [9](https://science.nasa.gov/solar-system/planets/planet-sizes-and-locations-in-our-solar-system/) Haumea is the third largest, with an equatorial diameter of about 1,080 miles (about 1,740 km), and [Makemake](https://www.edgepedia.org/makemake) is the third largest known object past Neptune's orbit, about two thirds the size of Pluto.[9](https://science.nasa.gov/solar-system/planets/planet-sizes-and-locations-in-our-solar-system/) • [10](https://science.nasa.gov/solar-system/resources/resource-packages/pluto-dwarf-planet-resources/)
All dwarf planets beyond Neptune's orbit are called plutoids, a term the IAU introduced for trans-Neptunian bodies large enough to be nearly round that have not cleared their orbits; satellites of plutoids are not themselves plutoids.[11](https://iauarchive.eso.org/public/themes/pluto/)
## The leading candidates
**Quaoar, Sedna, Orcus, and Gonggong** are the objects most often added to the official list. Live Science reports that astronomers who observe dwarf planets tend to recognize nine: the official five plus these four; Gonggong was discovered in 2007 and confirmed by new NASA telescope observations in 2016, and the IAU is still considering proposals on these bodies.[2](https://www.livescience.com/space/astronomy/what-are-dwarf-planets-and-how-many-are-there) A United Nations publication on solar-system exploration likewise lists Varuna, Quaoar, Orcus, and Sedna among large Kuiper Belt bodies ranging in size between Makemake and Ceres.[12](https://www.unoosa.org/pdf/publications/st_space_57E.pdf)
Quaoar illustrates how evidence accumulates. Stellar occultations, in which the body briefly blocks a background star, have refined its shape and size: a 2026 analysis of 28 occultations from 2018 to 2025 plus nine published events gives an equivalent volumetric diameter of 1,094.4 ± 4.6 km and a density of 1.760 ± 0.109 g/cm³, values compatible with a Maclaurin spheroid in hydrostatic equilibrium, which the authors state makes Quaoar eligible as a dwarf planet.[13](https://arxiv.org/abs/2607.06450) Quaoar also hosts two rings, the outer one orbiting at 7.4 body radii, well outside the classical [Roche limit](https://www.edgepedia.org/roche-limit) where dense rings were thought able to survive.[14](https://www.nature.com/articles/s41586-022-05629-6) • [15](https://www.esa.int/Science_Exploration/Space_Science/Cheops/ESA_s_Cheops_finds_an_unexpected_ring_around_dwarf_planet_Quaoar)
**2017 OF201** is the newest prominent candidate. A team led by Sihao Cheng of the [Institute for Advanced Study](https://www.edgepedia.org/institute-for-advanced-study), with Jiaxuan Li and Eritas Yang of Princeton University, identified it in archival images from the Victor M. Blanco [Telescope](https://www.edgepedia.org/telescope) and the [Canada-France-Hawaii Telescope](https://www.edgepedia.org/canada-france-hawaii-telescope), in 19 exposures spanning seven years; the IAU Minor Planet Center announced it on May 21, 2025.[16](https://www.ias.edu/news/extreme-cousin-pluto-possible-dwarf-planet-discovered-solar-systems-edge) Its orbit is extremely wide and eccentric, with a semi-major axis of 838 au, a perihelion of 44.9 au, and a period of 24,256 years; assuming a typical albedo of 0.15, the discoverers estimate a diameter of about 700 km, which would make it the second-largest known object in that dynamical population and a likely dwarf planet.[8](https://arxiv.org/abs/2505.15806) Because it spends only about 1 percent of its orbital time close enough to detect, the team estimates a hidden population of roughly a hundred similar objects, potentially totaling about 1 percent of Earth's mass.[8](https://arxiv.org/abs/2505.15806)
## Candidate lists and how many there may be
Several maintained lists track the candidates. [Michael E. Brown](https://www.edgepedia.org/michael-e-brown), the Caltech astronomer who led the surveys that discovered Eris, Haumea, Makemake, and others, publishes a continuously updated list; as of November 25, 2025 it counted 10 objects of near-certain dwarf-planet status and 27 that are highly likely, with "near certainty" defined as confidence that the object must be a dwarf planet even if predominantly rocky.[5](https://web.gps.caltech.edu/~mbrown/dps.html) An earlier NASA educational analysis notes that in August 2011 Brown published a list of 390 candidate dwarf planets ranging from "nearly certain" to "possible," including 2007 OR10 (Gonggong), Quaoar, Sedna, Orcus, 2002 MS4, and Salacia among the larger entries.[6](https://spacemath.gsfc.nasa.gov/Pluto/DwarfPlanetsV3.pdf) Gonzalo Tancredi, of the Universidad de la República in Uruguay, applied a decision tree based on size and light-curve shape to 46 trans-Neptunian objects estimated larger than 450 km and found 15 very probable plutoids plus possibly 9 more.[7](https://www.cambridge.org/core/journals/proceedings-of-the-international-astronomical-union/article/physical-and-dynamical-characteristics-of-icy-dwarf-planets-plutoids/5A9DBBF2EB1760433B97CF5A10AD274F)
**The total count is uncertain.** Estimates quoted in the scientific literature range from around 10 to a few hundred in the Kuiper Belt alone, with some estimates reaching tens of thousands beyond it.[2](https://www.livescience.com/space/astronomy/what-are-dwarf-planets-and-how-many-are-there) NASA states that there may be more than a hundred dwarf planets waiting to be discovered.[1](https://science.nasa.gov/dwarf-planets/) An objective classification scheme based on surface gravity, adopting a critical diameter of about 1,000 km and a critical density near 1 g/cm³ for Kuiper Belt objects, would place only seven bodies in the dwarf class: Pluto, Haumea, Quaoar, Makemake, Gonggong, Eris, and Sedna, while leaving mid-sized objects such as Orcus, Salacia, and 2002 XV93 in a borderline group.[17](https://www.mdpi.com/2075-4434/12/6/74)
## What observations of candidates show
Moons provide the masses that turn size estimates into density estimates, and densities in turn indicate whether a body is differentiated like a planet. Pluto has five moons, Eris one, Makemake one, Haumea two, and Ceres none.[18](https://www.space.com/astronomy/saturn/astronomers-keep-finding-new-moons-of-jupiter-and-saturn) Among the candidates, all but Sedna are known to have moons.[19](https://ova.gov.in/ovauploads/IandPRDeptRepository/04102025143651_-0-OR-Sept-Oct%20-2025.pdf)
Spectra of Sedna, Gonggong, and Quaoar taken by the [James Webb Space Telescope](https://www.edgepedia.org/james-webb-space-telescope) revealed ethane, acetylene, ethylene, water ice, carbon dioxide, and complex organic molecules, which the discoverers interpret as products of methane irradiation; they conclude that, like the larger dwarf planets but unlike every smaller Kuiper Belt object, all three bodies have experienced internal melting and geochemical evolution.[20](https://arxiv.org/abs/2309.15230) Such results support treating the largest candidates as planetary-mass worlds rather than simple icy rocks.
## References
1. [Pluto & Dwarf Planets, NASA Science](https://science.nasa.gov/dwarf-planets/)
2. [What are dwarf planets – and how many are there? Live Science](https://www.livescience.com/space/astronomy/what-are-dwarf-planets-and-how-many-are-there)
3. [IAU 2006 General Assembly: Result of the IAU Resolution votes](https://www.iau.org/IAU/Iau/News/PR2006/iau-2006-general-assembly-resolution-votes.aspx)
4. [What is a Planet? JPL Solar System Dynamics](https://ssd.jpl.nasa.gov/planets/def.html)
5. [Astronomer Mike Brown: Dwarf planets, Caltech](https://web.gps.caltech.edu/~mbrown/dps.html)
6. [Dwarf Planets, NASA Space Math](https://spacemath.gsfc.nasa.gov/Pluto/DwarfPlanetsV3.pdf)
7. [Tancredi, G. Physical and dynamical characteristics of icy "dwarf planets" (plutoids), Proceedings of the IAU](https://www.cambridge.org/core/journals/proceedings-of-the-international-astronomical-union/article/physical-and-dynamical-characteristics-of-icy-dwarf-planets-plutoids/5A9DBBF2EB1760433B97CF5A10AD274F)
8. [Cheng, S., Li, J., Yang, E. Discovery of a dwarf planet candidate in an extremely wide orbit: 2017 OF201, arXiv:2505.15806](https://arxiv.org/abs/2505.15806)
9. [Planet Sizes and Locations in Our Solar System, NASA Science](https://science.nasa.gov/solar-system/planets/planet-sizes-and-locations-in-our-solar-system/)
10. [Pluto and Dwarf Planet Resources, NASA Science](https://science.nasa.gov/solar-system/resources/resource-packages/pluto-dwarf-planet-resources/)
11. [Pluto and the Solar System, IAU](https://iauarchive.eso.org/public/themes/pluto/)
12. [United Nations Office for Outer Space Affairs, Solar System exploration publication](https://www.unoosa.org/pdf/publications/st_space_57E.pdf)
13. [Size, shape, density, and atmospheric limit of (50000) Quaoar revealed from 14 years of stellar occultation, arXiv:2607.06450](https://arxiv.org/abs/2607.06450)
14. [Morgado, B. E. et al. A dense ring of the trans-Neptunian object Quaoar outside its Roche limit, Nature 614, 239–243 (2023)](https://www.nature.com/articles/s41586-022-05629-6)
15. [ESA's Cheops finds an unexpected ring around dwarf planet Quaoar](https://www.esa.int/Science_Exploration/Space_Science/Cheops/ESA_s_Cheops_finds_an_unexpected_ring_around_dwarf_planet_Quaoar)
16. [An Extreme Cousin for Pluto? Possible Dwarf Planet Discovered at Solar System's Edge, Institute for Advanced Study](https://www.ias.edu/news/extreme-cousin-pluto-possible-dwarf-planet-discovered-solar-systems-edge)
17. [An Objective Classification Scheme for Solar-System Bodies Based on Surface Gravity, Geosciences (MDPI)](https://www.mdpi.com/2075-4434/12/6/74)
18. [Astronomers keep finding new moons of Jupiter and Saturn, Space.com](https://www.space.com/astronomy/saturn/astronomers-keep-finding-new-moons-of-jupiter-and-saturn)
19. [OR Sept–Oct 2025 publication on dwarf planets and moons](https://ova.gov.in/ovauploads/IandPRDeptRepository/04102025143651_-0-OR-Sept-Oct%20-2025.pdf)
20. [Emery, J. P. et al. A Tale of 3 Dwarf Planets: Ices and Organics on Sedna, Gonggong, and Quaoar from JWST Spectroscopy, arXiv:2309.15230](https://arxiv.org/abs/2309.15230)
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*Topic: Encyclopedia › Physical world and mathematics › Astronomy › Solar System › Solar System bodies › Dwarf planets and plutoids*
*Initially written Sep 17, 2026 · Reviewed: Oct 15, 2026 · Edited: Oct 15, 2026 · Last review: Oct 15, 2026*
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License: Edgepedia Community License 1.0, https://www.edgepedia.org/edgepedia/license