List of plutoid candidates
Encyclopedia
At present, the International Astronomical Union
classifies five objects as dwarf planet
s: , , , , and , though dozens of others are thought likely to be classified as such in the future. The qualifying feature of dwarf planets is that they must "have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium
(near-spherical shape)." Those dwarf planets lying beyond the orbit of Neptune
are termed "plutoids", after Pluto. Except for Pluto and Ceres, observations are insufficient for direct classification. However, based on present knowledge of how icy bodies gravitationally relax into equilibrium shapes, there are currently about 73 potential candidates amongst the population of trans-Neptunian object
s (TNOs). It is estimated that there are around 200 dwarf planets in the Kuiper belt
and up to 2000 in the region beyond. The first trans-Neptunian object discovered since Pluto that is a solid dwarf planet candidate is , and is estimated by the Spitzer Space Telescope
to be about 575 km in diameter.
less than +1 (and hence a mathematically-delimited minimum diameter of 838 km) will be overseen by two naming committees rather than one. Once named, the objects are declared to be dwarf planets by the IAU. Makemake and Haumea are the only TNOs to have proceeded through the naming process as presumed plutoids.
Mike Brown estimates that at a diameter somewhere between 200 and 400 km, an icy body relaxes into hydrostatic equilibrium. Thus, all TNOs listed are those known or suspected to be 400 km or above in diameter. However, diameter estimates vary widely, and they are therefore ordered here by their absolute magnitudes, H, rather than diameter. Theoretical minimum diameters correspond to a maximum albedo
of 1. But many borderline candidates are thought to be dark, and therefore substantially larger than this lower limit due to tholin
s causing a red-sloped reflectance spectrum
. Eris has a high albedo of 0.8–0.9, and the Haumea family
are also thought to be bright.
The list is also further complicated by smaller candidates such as 1999 TC36
that are discovered to be binary or triple systems. Plutino
1999 TC36 was resolved as a triple system by the Hubble
since the system is currently only 30.7 AU
from the Sun (just beyond the orbit of Neptune
).
At present, is the only identified dwarf planet in the asteroid belt
. At the time it announced the term "plutoid", the IAU noted that "current scientific knowledge lends credence to the belief that Ceres is the only object of its kind. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time." The likeliest exception would be 4 Vesta
, the asteroid belt's second-most massive body; Vesta appears to have a fully differentiated interior and was therefore at least in equilibrium at some point in its history. The third-most massive object, 2 Pallas
, has a somewhat irregular surface, and is thought to have only a partially differentiated interior. Mike Brown estimates that, since rocky objects become rounded far less easily than icy objects, rocky objects below 900 km in diameter may not be in hydrostatic equilibrium.
has estimated to have diameters greater than 600 km. is not included on this alpha list since it has not been observed by Spitzer. Even though has a dimmer absolute magnitude (H) than other objects on this list, it has a low albedo.
s have theoretical minimum diameters of 213–336 km.
Candidates with absolute magnitudes (H) dimmer than H=6, are not included since even assuming a dark albedo of 0.04 results in an estimated size less than 400 km.
The terms for varying degrees of likelihood are:
Another 288 objects were listed as "possible" dwarfs, depending on composition and the accuracy of size and mass estimates.
International Astronomical Union
The International Astronomical Union IAU is a collection of professional astronomers, at the Ph.D. level and beyond, active in professional research and education in astronomy...
classifies five objects as dwarf planet
Dwarf planet
A dwarf planet, as defined by the International Astronomical Union , is a celestial body orbiting the Sun that is massive enough to be spherical as a result of its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite...
s: , , , , and , though dozens of others are thought likely to be classified as such in the future. The qualifying feature of dwarf planets is that they must "have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium
Hydrostatic equilibrium
Hydrostatic equilibrium or hydrostatic balance is the condition in fluid mechanics where a volume of a fluid is at rest or at constant velocity. This occurs when compression due to gravity is balanced by a pressure gradient force...
(near-spherical shape)." Those dwarf planets lying beyond the orbit of Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
are termed "plutoids", after Pluto. Except for Pluto and Ceres, observations are insufficient for direct classification. However, based on present knowledge of how icy bodies gravitationally relax into equilibrium shapes, there are currently about 73 potential candidates amongst the population of trans-Neptunian object
Trans-Neptunian object
A trans-Neptunian object is any minor planet in the Solar System that orbits the Sun at a greater distance on average than Neptune.The first trans-Neptunian object to be discovered was Pluto in 1930...
s (TNOs). It is estimated that there are around 200 dwarf planets in the Kuiper belt
Kuiper belt
The Kuiper belt , sometimes called the Edgeworth–Kuiper belt, is a region of the Solar System beyond the planets extending from the orbit of Neptune to approximately 50 AU from the Sun. It is similar to the asteroid belt, although it is far larger—20 times as wide and 20 to 200 times as massive...
and up to 2000 in the region beyond. The first trans-Neptunian object discovered since Pluto that is a solid dwarf planet candidate is , and is estimated by the Spitzer Space Telescope
Spitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
to be about 575 km in diameter.
Changes to IAU naming procedures
The IAU has modified its nomenclature procedures such that objects considered highly likely to be plutoids receive differing treatment when receiving names than other TNOs. Objects that have an absolute magnitudeAbsolute magnitude
Absolute magnitude is the measure of a celestial object's intrinsic brightness. it is also the apparent magnitude a star would have if it were 32.6 light years away from Earth...
less than +1 (and hence a mathematically-delimited minimum diameter of 838 km) will be overseen by two naming committees rather than one. Once named, the objects are declared to be dwarf planets by the IAU. Makemake and Haumea are the only TNOs to have proceeded through the naming process as presumed plutoids.
Candidates
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
of 1. But many borderline candidates are thought to be dark, and therefore substantially larger than this lower limit due to tholin
Tholin
Tholin [after the ancient Greek word meaning "not clear"] is a heteropolymer molecule formed by solar ultraviolet irradiation of simple organic compounds such as methane or ethane. Tholins do not form naturally on modern-day Earth, but are found in great abundance on the surface of icy bodies in...
s causing a red-sloped reflectance spectrum
Spectral slope
In astrophysics and planetary science, spectral slope, also called spectral gradient , is a measure of dependence of the reflectance on the wavelength....
. Eris has a high albedo of 0.8–0.9, and the Haumea family
Haumea family
The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body...
are also thought to be bright.
The list is also further complicated by smaller candidates such as 1999 TC36
(47171) 1999 TC36
' is a system comprising three trans-Neptunian objects . It was discovered in 1999 by Eric P. Rubenstein and Louis-Gregory Strolger during an observing run at Kitt Peak National Observatory . Dr. Rubenstein was searching images taken by Dr. Strolger as part of the Low-Z Supernova Search program...
that are discovered to be binary or triple systems. Plutino
Plutino
In astronomy, a plutino is a trans-Neptunian object in 2:3 mean motion resonance with Neptune. For every 2 orbits that a plutino makes, Neptune orbits 3 times. Plutinos are named after Pluto, which follows an orbit trapped in the same resonance, with the Italian diminutive suffix -ino...
1999 TC36 was resolved as a triple system by the Hubble
Hubble Space Telescope
The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...
since the system is currently only 30.7 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....
from the Sun (just beyond the orbit of Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
).
At present, is the only identified dwarf planet in the asteroid belt
Asteroid belt
The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets...
. At the time it announced the term "plutoid", the IAU noted that "current scientific knowledge lends credence to the belief that Ceres is the only object of its kind. Therefore, a separate category of Ceres-like dwarf planets will not be proposed at this time." The likeliest exception would be 4 Vesta
4 Vesta
Vesta, formally designated 4 Vesta, is one of the largest asteroids, with a mean diameter of about . It was discovered by Heinrich Wilhelm Olbers on March 29, 1807, and is named after the Roman virgin goddess of home and hearth, Vesta....
, the asteroid belt's second-most massive body; Vesta appears to have a fully differentiated interior and was therefore at least in equilibrium at some point in its history. The third-most massive object, 2 Pallas
2 Pallas
Pallas, formally designated 2 Pallas, is the second asteroid to have been discovered , and one of the largest. It is estimated to constitute 7% of the mass of the asteroid belt, and its diameter of 530–565 km is comparable to, or slightly larger than, that of 4 Vesta. It is however 20%...
, has a somewhat irregular surface, and is thought to have only a partially differentiated interior. Mike Brown estimates that, since rocky objects become rounded far less easily than icy objects, rocky objects below 900 km in diameter may not be in hydrostatic equilibrium.
Spitzer alpha candidates
The following alpha list only contains candidates that the Spitzer Space TelescopeSpitzer Space Telescope
The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003...
has estimated to have diameters greater than 600 km. is not included on this alpha list since it has not been observed by Spitzer. Even though has a dimmer absolute magnitude (H) than other objects on this list, it has a low albedo.
| Name | (H) | Spitzer Spitzer Space Telescope The Spitzer Space Telescope , formerly the Space Infrared Telescope Facility is an infrared space observatory launched in 2003... Size (km) | Spitzer Albedo |
V–R |
|---|---|---|---|---|
| 1.6 | <1600 | >0.16 | 0.78 | |
| 3.8 | 1150 | 0.03 | 0.67 | |
| 2.3 | 946 | 0.28±0.04 | 0.37 | |
| 2.5 | 844 | 0.199 | 0.64 | |
| 3.2 | 734 | 0.117 | 0.56 | |
| 4.0 | 725 | 0.058 | 0.59 | |
| 3.8 | 726 | 0.084 | 0.38 | |
| 4.0 | 686 | 0.12 | 0.36 | |
| 3.6 | 681 | 0.115 | 0.57 | |
| 3.9 | 677 | 0.08±0.02 | 0.52 | |
| 3.2 | 650 | 0.12 | 0.61 |
Under 3
These TNOs are over a thousand km across when assuming a generic albedo of 0.09, and have theoretical minimum diameters greater than 334 km.| Name | |H | |Category | |Diameter (km) | |Min. diam. | |Mass (1020 kg) | |Average distance from the Sun (AU Astronomical unit An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance.... ) |
||
|---|---|---|---|---|---|---|---|---|
| by | by | others | ||||||
| 1.58 | detached object Detached object (astronomy) Detached objects are a dynamical class of bodies in the outer Solar System beyond the orbit of Neptune. These objects have orbits whose points of closest approach to the Sun are sufficiently distant from the gravitational influence of Neptune that they are essentially unaffected by Neptune and the... |
1800 | 1700 | < 1600 | 650 | 8.3–70? | 486.0 | |
| 2.00 | SDO Scattered disc The scattered disc is a distant region of the Solar System that is sparsely populated by icy minor planets, a subset of the broader family of trans-Neptunian objects. The scattered-disc objects have orbital eccentricities ranging as high as 0.8, inclinations as high as 40°, and perihelia greater... |
1834 | 900–1400 | 532 | 67 | |||
| 2.30 | plutino Plutino In astronomy, a plutino is a trans-Neptunian object in 2:3 mean motion resonance with Neptune. For every 2 orbits that a plutino makes, Neptune orbits 3 times. Plutinos are named after Pluto, which follows an orbit trapped in the same resonance, with the Italian diminutive suffix -ino... |
1100 | 901 | 875–1020 | 460 | 6.32 | 39.34 | |
| 2.48 | cubewano Cubewano A classical Kuiper belt object, also called a cubewano is a low-eccentricity Kuiper belt object that orbits beyond Neptune and is not controlled by an orbital resonance with Neptune. Cubewanos have orbits with semi-major axes in the 40–50 AU range and, unlike Pluto, do not cross Neptune’s orbit... |
1290 | 842 | 820–960 | 426 | 13–19 | 43.58 |
Between 3 and 4
These minor planetMinor planet
An asteroid group or minor-planet group is a population of minor planets that have a share broadly similar orbits. Members are generally unrelated to each other, unlike in an asteroid family, which often results from the break-up of a single asteroid...
s have theoretical minimum diameters of 213–336 km.
| Name | |H | |Category | |Diameter (km) | |Mass (1020 kg) | |Average distance from the Sun (AU) |
||
|---|---|---|---|---|---|---|---|
| by | by | others | |||||
| 3.19 | haumeid Haumea family The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body... |
800 | 709 | 286 | 0.2 | 43.11 | |
| Vesta 4 Vesta Vesta, formally designated 4 Vesta, is one of the largest asteroids, with a mean diameter of about . It was discovered by Heinrich Wilhelm Olbers on March 29, 1807, and is named after the Roman virgin goddess of home and hearth, Vesta.... |
3.20 | asteroid Asteroid Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones... |
578×560×458 km | 2.59 | 2.361 | ||
| 3.20 | plutino | 980 | 727 | 430–910; 900–1230 | ~3? | 39.65 | |
| 3.26 | cubewano | 940 | 766 | 625–850; 770–1010 | ~4? | 47.30 | |
| 3.40 | SDO | 919 | 925 (550–1240) | 113 | |||
| 3.40 | cubewano | 919 | 925 (550–1240) | 43 | |||
| (229762) 2007 UK126 | 3.40 | SDO | 919 | 530–1190 | 73 | ||
| 3.40 | cubewano | 740 | 838 | 45.94 | |||
| 3.60 | cubewano | 810 | 649 | 570–795 | ~3? | 42.53 | |
| 3.70 | cubewano | 780 | 785 | 755–1025; 480–800 | 42.90 | ||
| 3.70 | cubewano | 1008 | 1015 | 47.99 | |||
| 3.77 | cubewano | 740 | 728 | 600–850 | 41.90 | ||
| 3.80 | semi-detached Detached object (astronomy) Detached objects are a dynamical class of bodies in the outer Solar System beyond the orbit of Neptune. These objects have orbits whose points of closest approach to the Sun are sufficiently distant from the gravitational influence of Neptune that they are essentially unaffected by Neptune and the... |
765 | 67.3 | ||||
| 3.81 | SDO | 765 | 462–1033 | 69.4 | |||
| 3.87 | 5:2 Resonant trans-Neptunian object In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object 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, 2:3 etc... SDO |
710 | 1150 | 920–1480 | ~15? | 55.02 | |
| 3.90 | cubewano | 740 | 730 | 41.53 | |||
| 3.90 | cubewano | 680 | 681 | 610–750 | ~3? | 42.23 | |
| 3.90 | SDO | 697 | 421-942 | 184.4 | |||
| 3.95 | haumeid Haumea family The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body... |
650 | 666 | 230 km | 43.24 | ||
| 3.99 | plutino Plutino In astronomy, a plutino is a trans-Neptunian object in 2:3 mean motion resonance with Neptune. For every 2 orbits that a plutino makes, Neptune orbits 3 times. Plutinos are named after Pluto, which follows an orbit trapped in the same resonance, with the Italian diminutive suffix -ino... |
610 | 636 | 540–925 | 39.27 | ||
Between 4 and 5
| Name | |H | |Category | |Diameter (km) | |Mass (1020 kg) | |Average distance from the Sun (AU) |
||
|---|---|---|---|---|---|---|---|
| by | by | others | |||||
| 4.0 | haumeid Haumea family The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body... |
697 | 252 km | 43 | |||
| 4.0 | plutino | 710 | 686 | 590–785 km | 39.45 | ||
| 4.0 | cubewano | 696 | 46.98 | ||||
| 4.05 | 9:4 Resonant trans-Neptunian object In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object 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, 2:3 etc... SDO |
620 | 636 | 51.40 | |||
| Pallas 2 Pallas Pallas, formally designated 2 Pallas, is the second asteroid to have been discovered , and one of the largest. It is estimated to constitute 7% of the mass of the asteroid belt, and its diameter of 530–565 km is comparable to, or slightly larger than, that of 4 Vesta. It is however 20%... |
4.13 | asteroid Asteroid Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones... |
582×556×500±9 km |
2.11±0.26 |
2.772 | ||
| 4.2 | cubewano | 380-860 | 45.8 | ||||
| 4.2 | cubewano | 380-860 | 46.5 | ||||
| 120347 Salacia | 4.3 | cubewano | 560 | 548 | 41.97 | ||
| 4.3 | plutino | 591 | |||||
| 4.3 | other TNO | 540 | 554 | 38.72 | |||
| 4.4 | cubewano | 350-784 | 44.4 | ||||
| 4.4 | cubewano | 580 | 350-784 | 44.05 | |||
| 4.4 | SDO | 210 Haumea family The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body... -584 |
54.2 | ||||
| 4.4 | SDO | 583 | 350-784 | 106 | |||
| 4.4 | SDO | 560 | 580 | 89.73 | |||
| 4.4 | cubewano | 580 | |||||
| (Buffy) | 4.47 | SDO | 540 | 572 | 57.36 | ||
| 4.5 | cubewano | 330-750 | 42 | ||||
| 4.5 | cubewano? | 560 | 560 | <560(?) | 39.01 | ||
| 4.5 | plutino | 529 | 39.1 | ||||
| 4.56 | haumeid Haumea family The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body... |
540 | 900 | 200 km | 43.19 | ||
| 4.6 | lost | 520 | 522 | ~45 | |||
| 4.7 | cubewano | 305-680 | 43.2 | ||||
| 4.7 | plutino | 490 | 420 | 39.30 | |||
| 4.7 | 2:5 Resonant trans-Neptunian object In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object 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, 2:3 etc... TNO |
490 | 461 | 461±45 | 1? | 55.72 | |
| 38628 Huya 38628 Huya 38628 Huya is a trans-Neptunian object . It was discovered in March 2000 by Ignacio Ferrin and announced on 24 October 2000. It is classified as a plutino being in a 2:3 mean motion resonance with Neptune. With a Spitzer size estimate of , this plutino is also a likely dwarf-planet. It is expected... |
4.7 | plutino | 480 | 506 | 532±25 | 1.6? | 39.76 |
| 4.7 | detached | 505 | 76.38 | ||||
| 4.7 | plutino | 505 | 39.18 | ||||
| 4.73 | plutino | 440 | A1=286 A2=265 | 0.12 | 39.27 | ||
| 4.7 | plutino | 522 | 39.56 | ||||
| 4.7 | detached | 450 | 505 | 49.9 | |||
| 4.8 | haumeid Haumea family The Haumea family is the only identified trans-Neptunian collisional family; that is, the only group of trans-Neptunian objects with similar orbital parameters and spectra that suggest they originated in the disruptive impact of a progenitor body... |
470 | 702 | 174 km | 41.64 | ||
| 4.8 | detached Detached object (astronomy) Detached objects are a dynamical class of bodies in the outer Solar System beyond the orbit of Neptune. These objects have orbits whose points of closest approach to the Sun are sufficiently distant from the gravitational influence of Neptune that they are essentially unaffected by Neptune and the... |
430 | 440 | 49.77 | |||
| 4.8 | 8:3 Resonant trans-Neptunian object In astronomy, a resonant trans-Neptunian object is a trans-Neptunian object 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, 2:3 etc... TNO |
430 | 431 | 57.77 | |||
| 19521 Chaos 19521 Chaos 19521 Chaos , is a cubewano, a Kuiper-belt object not in resonance with any planet. It is a likely dwarf planet. Chaos was discovered in 1998 by the Deep Ecliptic Survey, with Kitt Peak's 4 m telescope. Assuming it has an albedo of 0.09, the absolute magnitude of 4.9 would make it about... |
4.9 | cubewano | 450 | 745 | 45.56 | ||
| 4.9 | plutino | 430 | 457 | 39.22 | |||
| 4.9 | cubewano | 410 | 440 | 46.18 | |||
| 4.9 | SDO | 461 | 67 | ||||
| 5.0 | cubewano | 430 | 440 | 44.65 |
Above 5
| Name | H | Category | Diameter (km) | Average distance from the Sun (AU) |
|---|---|---|---|---|
| 5.0 | twotino | 410, 400 | 47.67 | |
| 5.1 | cubewano | 410, 305 | 43.87 | |
| 5.1 | SDO | 410, 426 | 43.69 | |
| 5.2 | SDO | 401 | 94.88 | |
| 5.2 | lost | 400 | ~56 | |
| 5.4 | SDO | 632, 460-690 | 83 | |
| 5.4 | cubewano | 560, 396 | 43.65 | |
| Hygiea 10 Hygiea 10 Hygiea is an asteroid located in the asteroid belt. With somewhat oblong diameters of 350–500 km, and a mass estimated to be 2.9% of the total mass of the belt, it is the fourth largest asteroid by volume and mass... |
5.43 | asteroid Asteroid Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones... |
500×385×350 | 3.139 |
| 5.3 | SDO | 510, 440 | 47.08 | |
| 5.8 | cubewano | 460 | 37.93 |
Candidates with absolute magnitudes (H) dimmer than H=6, are not included since even assuming a dark albedo of 0.04 results in an estimated size less than 400 km.
Probable per Brown
Mike Brown considers the following bodies, ranked by estimated size, to be "probably" plutoids. Asteroids are not considered.The terms for varying degrees of likelihood are:
- Near certainty: Sufficient confidence to say these must be in hydrostatic equilibrium even if predominantly rocky.
- Highly likely: Estimated/measured to be over 600 km. The size would have to be "grossly in error" or they would have to be primarily rocky to not be dwarf planets.
- Likely: Estimated/measured to be over 500 km. Uncertainties in measurement mean that some of these will be significantly smaller and thus doubtful.
- Probable: Estimated/measured to be over 400 km. Expected to be dwarf planets if they are icy and that figure is correct.
| rank | name | diameter (km) |
albedo (%) |
absolute magnitude (H) |
comments | likelihood |
|---|---|---|---|---|---|---|
| 1 | 2330 | 99 | −1.1 | (measured) | near certainty | |
| 2 | Pluto Pluto Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System and the tenth-most-massive body observed directly orbiting the Sun... |
2330 | 66 | −0.7 | (measured) | near certainty |
| 3 | 1500 | 69 | 0.2 | (measured) | near certainty | |
| 4 | 1440 | 79 | 0.1 | (measured) | near certainty | |
| 5 | 2007 OR10 | 1420 | 19 | 1.7 | (estimate) | near certainty |
| 6 | 1400 | 22 | 1.6 | (estimate) | near certainty | |
| 7 | 2002 TC302 | 1150 | 4 | 3.8 | (very large uncertainty: likely smaller) |
highly likely |
| 8 | 980 | 18 | 2.6 | (measured) | near certainty | |
| 9 | 950 | 25 | 2.3 | (measured) | near certainty | |
| 10 | 2007 UK126 2007 UK126 ', also written as 2007 UK126, is a scattered disc object with a bright absolute magnitude of 3.4. This qualifies it as one of the largest dwarf-planet candidates. , Mike Brown lists it as a highly likely dwarf planet.... |
748 | 15 | 3.4 | highly likely | |
| 11 | 2005 QU182 2005 QU182 ', also written as 2005 QU182, is a trans-Neptunian object with a bright absolute magnitude of 3.4. This qualifies it as one of the largest dwarf-planet candidates... |
748 | 15 | 3.4 | highly likely | |
| 12 | 2003 MW12 | 748 | 15 | 3.4 | highly likely | |
| 13 | 2005 UQ513 | 748 | 15 | 3.4 | highly likely | |
| 14 | 2002 AW197 | 734 | 15 | 3.4 | (measured) | highly likely |
| 15 | 2002 MS4 2002 MS4 ' is a Trans-Neptunian object . It was discovered in 2002 by Chad Trujillo and Michael E. Brown. It is classified as a cubewano by the Minor Planet Center.It is very likely a dwarf planet... |
726 | 12 | 3.7 | (measured) | highly likely |
| 16 | 2007 JJ43 2007 JJ43 ' is a trans-Neptunian object orbiting the Sun near the outer edge of the Kuiper belt. Based on how bright it appears in telescopes, it is thought likely to be a plutoid , but is not yet formally recognized as such by the International Astronomical Union.Its discovery images were taken in 2007... |
694 | 13 | 3.7 | highly likely | |
| 17 | 2003 AZ84 2003 AZ84 ', also written as 2003 AZ84, is a plutino, like Pluto, in a 2:3 resonance with Neptune. It is very likely a dwarf planet. It was discovered on January 13, 2003 by C. Trujillo and M. Brown using the Samuel Oschin telescope in the Palomar Observatory... |
685 | 15 | 3.6 | (measured) | highly likely |
| 18 | 2002 UX25 | 681 | 13 | 3.7 | (measured) | highly likely |
| 19 | 2006 QH181 2006 QH181 ', also written as 2006 QH181, is a trans-Neptunian object. It is very likely a dwarf planet. It is part of the scattered disc. It may be a detached object since a perihelion of 37.6 AU may place it outside of the direct influence of Neptune, or it could have a 5:1 resonance with Neptune... |
677 | 12 | 3.8 | highly likely | |
| 20 | 2010 EK139 2010 EK139 ' is a trans-Neptunian object orbiting the Sun in the scattered disc. It was discovered in 2010 by astronomers from the OGLE team led by Andrzej Udalski from Warsaw University... |
677 | 12 | 3.8 | highly likely | |
| 21 | 2004 GV9 | 677 | 10 | 4.0 | (measured) | highly likely |
| 22 | 2005 RN43 | 661 | 12 | 3.9 | highly likely | |
| 23 | 2010 KZ39 2010 KZ39 ', also written as 2010 KZ39, is a trans-Neptunian object with an absolute magnitude of 3.9. It is very likely a dwarf planet.-Characteristics:It has been observed 19 times over two oppositions. It is currently 46.3 AU from the Sun... |
661 | 12 | 3.9 | highly likely | |
| 24 | 650 | 21 | 3.3 | (measured) | highly likely | |
| 25 | 2004 XA192 | 644 | 11 | 4.0 | highly likely | |
| 26 | 2003 VS2 | 629 | 11 | 4.1 | highly likely | |
| 27 | 2001 UR163 | 613 | 10 | 4.2 | highly likely | |
| 28 | 613 | 10 | 4.2 | highly likely | ||
| 29 | 2004 PF115 | 613 | 10 | 4.2 | highly likely | |
| 30 | 2010 RF43 | 613 | 10 | 4.2 | highly likely | |
| 31 | 2010 RE64 2010 RE64 ', also written as 2010 RE64, is a trans-Neptunian object with an absolute magnitude of 4.2. It is very likely a dwarf planet.-Preliminary:... |
613 | 10 | 4.2 | highly likely | |
| 32 | 2008 ST291 2008 ST291 ', also written as 2008 ST291, is a trans-Neptunian object with an absolute magnitude of 4.4. This makes it a dwarf-planet candidate.-Distance:It came to perihelion around 1954, and is currently 56.8 AU from the Sun.... |
598 | 10 | 4.3 | likely | |
| 33 | 2003 UZ413 2003 UZ413 ', also written as 2003 UZ413, is a trans-Neptunian object with an absolute magnitude of 4.4. A 2:3 orbital resonance with Neptune makes it a plutino... |
598 | 10 | 4.3 | likely | |
| 34 | 2010 FX86 | 598 | 10 | 4.3 | likely | |
| 35 | 2005 RM43 (145451) 2005 RM43 ', also written as 2005 RM43, is a trans-Neptunian object that resides in the scattered disc region beyond the Kuiper belt. It was discovered on September 9, 2005 by Andrew C. Becker, Andrew W. Puckett, and Jeremy Martin Kubica at Apache Point Observatory in Sunspot, New Mexico.It has been... |
584 | 10 | 4.4 | likely | |
| 36 | 2004 XR190 2004 XR190 ' is a dwarf-planet candidate located in the scattered disc. Astronomers led by Lynne Jones of the University of British Columbia made the discovery as part of the using the Canada-France-Hawaii Telescope... |
584 | 10 | 4.4 | likely | |
| 37 | 2002 KX14 | 584 | 10 | 4.4 | likely | |
| 38 | 2004 NT33 2004 NT33 ' is a member of the Kuiper belt discovered in 2004. It is classified as cubewano. As of 2011, it is thought to have a diameter of about 580 km. This is up from 554 km in 2008.It is currently 38.2 AU from the Sun.- External links :*... |
584 | 10 | 4.4 | likely | |
| 39 | 1996 TL66 | 575 | 4 | 5.4 | (measured) | likely |
| 40 | 2004 TY364 | 569 | 9 | 4.5 | likely | |
| 41 | 2004 UX10 | 569 | 9 | 4.5 | likely | |
| 42 | 2008 AP129 | 569 | 9 | 4.5 | likely | |
| 43 | 2010 VK201 | 569 | 9 | 4.5 | likely | |
| 44 | 2004 PR107 | 555 | 9 | 4.6 | likely | |
| 45 | 2005 TB190 | 542 | 8 | 4.7 | likely | |
| 46 | 2003 QX113 2003 QX113 ', also written as 2003 QX113, is a detached object that was discovered when it was near aphelion. With an absolute magnitude of 4.9, it may qualify as a small dwarf-planet candidate.... |
542 | 8 | 4.7 | likely | |
| 47 | 2007 JH43 2007 JH43 ', also written as 2007 JH43, is a trans-Neptunian object with an absolute magnitude of 4.7. This may qualify it as a small dwarf-planet candidate... |
542 | 8 | 4.7 | likely | |
| 48 | 532 | 7 | 4.9 | (measured) | likely | |
| 49 | 2010 VZ98 | 528 | 8 | 4.8 | likely | |
| 50 | 528 | 8 | 4.8 | likely | ||
| 51 | 2000 YW134 | 515 | 8 | 4.9 | likely | |
| 52 | 2004 PG115 | 515 | 8 | 4.9 | likely | |
| 53 | 2008 QY40 | 515 | 8 | 4.9 | likely | |
| 54 | 2003 FY128 | 515 | 8 | 4.9 | likely | |
| 55 | 2008 OG19 | 503 | 7 | 5.0 | likely | |
| 56 | 2001 KA77 | 503 | 7 | 5.0 | likely | |
| 57 | 2002 KW14 | 503 | 7 | 5.0 | likely | |
| 58 | 2002 XV93 2002 XV93 ', also written as 2002 XV93, is a trans-Neptunian object with an absolute magnitude of 4.7. A 2:3 orbital resonance with Neptune makes it a plutino.It has been observed with precovery images back to 1990.- Orbit and rotation :... |
503 | 7 | 5.0 | likely | |
| 59 | 2007 XV50 | 503 | 7 | 5.0 | likely | |
| 60 | 2011 FW62 | 503 | 7 | 5.0 | likely | |
| 61 | 500 | 27 | 3.6 | (measured) | probable | |
| 62 | 2002 WC19 | 490 | 7 | 5.1 | probable | |
| 63 | 1999 CD158 1999 CD158 ', also written as 1999 CD158, is a trans-Neptunian object that resides in the Kuiper belt with orbital resonance with Neptune 4:7, i.e. for every seven orbits of Neptune around the Sun, this makes four. Its diameter is about 420 km.... |
490 | 7 | 5.1 | probable | |
| 64 | 2001 QF298 2001 QF298 ', also written as 2001 QF298, is a trans-Neptunian object that resides in the Kuiper belt. It was discovered on August 19, 2001 by Marc W. Buie. is a plutino, meaning that it is locked in a 3:2 orbital resonance with Neptune much like Pluto... |
490 | 7 | 5.1 | probable | |
| 65 | 2010 EL139 | 490 | 7 | 5.1 | probable | |
| 66 | 2010 RO64 | 490 | 7 | 5.1 | probable | |
| 67 | 2011 GM27 | 490 | 7 | 5.1 | probable | |
| 68 | 1996 GQ21 (26181) 1996 GQ21 ', also written as 1996 GQ21, is a trans-Neptunian object that resides in the scattered disc region of the Solar System. It was discovered on April 12, 1996 by Nichole M. Danzl.-References:... |
478 | 7 | 5.2 | probable | |
| 69 | 2006 HH123 2006 HH123 ', also written as 2006 HH123, is a lost scattered-disc object. With an absolute magnitude of 5.2, it is a dwarf-planet candidate. The preliminary orbital elements as displayed in the infobox are calculated using only three observations over a period of one day, hence its orbit is very poorly known... |
478 | 7 | 5.2 | probable | |
| 70 | 2010 ET65 | 478 | 7 | 5.2 | probable | |
| 71 | 2010 TY53 | 478 | 7 | 5.2 | probable | |
| 72 | 2008 UA332 | 478 | 7 | 5.2 | probable | |
| 73 | 2010 HE79 | 478 | 7 | 5.2 | probable | |
| 74 | 2002 PJ149 | 467 | 7 | 5.3 | probable | |
| 75 | 2003 UA414 | 467 | 7 | 5.3 | probable | |
| 76 | 2005 RS43 | 467 | 7 | 5.3 | probable | |
| 77 | 2010 JK124 | 467 | 7 | 5.3 | probable | |
| 78 | 2010 PU75 | 467 | 7 | 5.3 | probable | |
| 79 | 1999 DE9 | 461 | 8 | 5.1 | (measured) | probable |
| 80 | 1998 SN165 | 460 | 5 | 5.6 | (measured) | probable |
| 81 | 1995 TL8 | 455 | 6 | 5.4 | probable | |
| 82 | 2008 CT190 | 455 | 6 | 5.4 | probable | |
| 83 | 2010 ER65 | 455 | 6 | 5.4 | probable | |
| 84 | 2010 TR19 | 455 | 6 | 5.4 | probable | |
| 85 | 2002 GJ32 | 455 | 6 | 5.4 | probable | |
| 86 | 2001 QS297 | 455 | 6 | 5.4 | probable | |
| 87 | 2002 CY248 | 455 | 6 | 5.4 | probable | |
| 88 | 2003 QW90 2003 QW90 ', also written as 2003 QW90, is a trans-Neptunian object that resides in the Kuiper belt. It was discovered on August 23, 2003, by Marc W. Buie.Diameter by 2008 was listed as 440 km.-References:... |
455 | 6 | 5.4 | probable | |
| 89 | 2007 PS45 | 455 | 6 | 5.4 | probable | |
| 90 | 2002 JR146 | 444 | 6 | 5.5 | probable | |
| 91 | 2010 TJ | 444 | 6 | 5.5 | probable | |
| 92 | 2002 XW93 | 444 | 6 | 5.5 | probable | |
| 93 | 2001 YH140 | 444 | 6 | 5.5 | probable | |
| 94 | 2001 XD255 | 444 | 6 | 5.5 | probable | |
| 95 | 2002 GH32 | 444 | 6 | 5.5 | probable | |
| 96 | 2002 XH91 | 444 | 6 | 5.5 | probable | |
| 97 | 2010 EP65 | 444 | 6 | 5.5 | probable | |
| 98 | 1999 TC36 | 415 | 12 | 4.9 | (measured) | probable |
| 99 | 2001 FP185 | 411 | 4 | 6.0 | (blue) | probable |
| 100 | 2000 CQ105 | 411 | 4 | 6.0 | (blue) | probable |
| 101 | 2001 QX322 | 411 | 4 | 6.0 | (blue) | probable |
| 102 | 1999 CL119 | 411 | 4 | 6.0 | (blue) | probable |
Another 288 objects were listed as "possible" dwarfs, depending on composition and the accuracy of size and mass estimates.
External links
- How many dwarf planets are there in the outer solar system? (updates daily) (Mike Brown)
- Details on the dwarf planet size calculations (Mike Brown)
- Which are the Dwarfs in the Solar System? Tancredi,G; Favre,S. Icarus, Volume 195, Issue 2, p. 851-862.
- NASA JPL Small-Body Database Search Engine