Known populations of solar system objects: 17 November 2020

compiled by Wm. Robert Johnston
last updated 6 December 2020

For related historical graphs see Historical known populations of solar system objects.

Summary

Star: 1

Planets*: 8
Dwarf planets*: 5 (5 named)
Asteroids*: 1,024,991 (546,059 numbered, 478,932 provisional)
Outer solar system objects*: 3,814 (782 numbered, 2,997 provisional, 35 without official designations)
Comets**: 6,996 (394 numbered**, 3,816 with provisional designations, 2,786 without official designations)

Interstellar objects: 2 (2 numbered)

Moons of planets: 208 (169 numbered, 36 provisional, 3 without official designations)
Moons of dwarf planets: 9 (8 numbered, 1 provisional)
Moons of asteroids: 316 (15 numbered, 20 provisional, 281 without official designations)
Moons of outer solar system objects: 111 (17 numbered, 2 provisional, 92 without official designations)

Objects with ring systems: 6 (4 planets, 1 dwarf planet, 1 Centaur)

Total objects: 1,036,458 (547,460 with permanent designations, 485,804 with provisional designations, 3,194 without official designations)

Objects with names:
--1 star, 8 planets, 5 dwarf planets, 21,878 asteroids, 44 outer solar system objects
--149 planet moons, 8 dwarf planet moons, 15 asteroid moons, 17 outer solar system object moons
--6,101 comets, 2 interstellar objects

Counts are based on current officially assigned permanent or provisional designations with exceptions as noted in the notes and table below. Counts are up-to-date through 17 November 2020 with these exceptions: none.

* Note: "dwarf planet" is a new classification invented by the International Astronomical Union (IAU) in August 2006. At that time the IAU declared Pluto a dwarf planet but not a planet, and also classified (136199) Eris and (1) Ceres as dwarf planets. In July 2008 (136472) Makemake was declared the fourth dwarf planet, and in September 2008 (136108) Haumea the fifth. Though those classifications are still disputed, these five objects are not included here in the counts of asteroids and outer solar system objects, and Pluto is not included in the count of planets. At least one more outer solar system object, (225088) Gonggong, should be in this group, but since the IAU has not applied their definition in this case it is not counted as a dwarf planet.

** Note: excludes two objects with dual asteroid/comet designations counted among Centaurs (Chiron and Echeclus) and seven objects with dual asteroid/comet designations counted among numbered asteroids.


Known populations of solar system objects--detail

type of objecttotalpermanent designationprovisional designationno official designationfirst one discovered
[year discovered]
notes
star 1 1 0 0Sun
planets 8 8 0 0EarthAs currently defined by IAU.
dwarf planets 5 5 0 0(1) Ceres
[discovered 1801]
As currently defined by IAU.
--Mercury moons 0 0 0 0(none)
asteroids, Atira 23 6 17 0(163693) Atira
[discovered 2003]
Asteroids with orbits entirely inside the Earth's orbit.
--Atira asteroid moons 1 0 0 1
[discovered 2017]
--Venus moons 0 0 0 0(none)
asteroids, Aten 1,838 237 1,601 0(2062) Aten
[discovered 1976]
Asteroids with semimajor axes less than 1.0 AU.
--Aten asteroid moons 7 1 0 6
[discovered 1999]
--Earth moons 1 1 0 0Moon
asteroids, Earth Trojans 1 0 1 02010 TK7
[discovered 2010]
Asteroid orbiting the Sun in Earth's L4 and L5 positions (60 degrees ahead of and behing Earth, respectively). Does not include non-Trojan coorbital objects, such as 2002 AA29.
asteroids, Apollo 13,396 1,473 11,923 0(1862) Apollo
[discovered 1932]
Asteroids (other than Atens and Earth trojans) crossing the Earth's orbit.
--Apollo asteroid moons 48 1 3 44
[discovered 1997]
asteroids, Amor 9,013 1,202 7,811 0(433) Eros
[discovered 1898]
Asteroids (other than Aitras, Atens, Apollos, or Earth trojans) with perihelion distances less than 1.3 AU.
--Amor asteroid moons 25 0 0 25
[discovered 1997]
--Mars moons 2 2 0 0Phobos
[discovered 1877]
asteroids, Mars Trojans 9 5 4 0(5261) Eureka
[discovered 1990]
Asteroids orbiting the Sun in Mars' L4 and L5 positions (60 degrees ahead of and behind Mars, respectively).
--Mars Trojan asteroid moons 1 0 0 1
[discovered 2014]
asteroids, Mars crossers 19,971 5,470 14,501 0(132) Aethra
[discovered 1873]
Asteroids (other than Atiras, Atens, Apollos, or Mars trojans) crossing Mars' orbit.
--Mars crosser asteroid moons 31 0 1 30
[discovered 2014]
asteroids, main belt 971,829532,593439,236 0
(2) Pallas
[discovered 1802]
Asteroids not counted elsewhere (some may cross the orbits of Mars, Jupiter, or other outer planets). Provisional asteroid figures include many objects counted more than once.
--main belt asteroid moons 197 11 15 171Dacytl
[discovered 1993]
--Ceres moons 0 0 0 0(none)
comets, Jupiter family 746 371 375 0Comets with Tisserand parameter with respect to Jupiter less than 2 (generally, comets with periods less than 20 years).
--Jupiter moons 79 72 7 0Io, Europa, Ganymede, and Callisto
[discovered 1610]
Does not include 57 objects without computed orbits.
asteroids, Jupiter Trojans 8,622 5,051 3,571 0(588) Achilles
[discovered 1906]
Asteroids orbiting the Sun in Jupiter's L4 and L5 positions (60 degrees ahead of and behind Jupiter, respectively).
--Jupiter Trojan asteroid moons 6 2 1 3Menoetius
[discovered 2001]
asteroids, other unusual 289 22 267 0(944) Hidalgo
[discovered 1920]
Asteroids with aphelion distances greater than 7.5 AU, other than those in other categories.
--Saturn moons 85 53 29 3Titan
[discovered 1655]
Includes 3 persistent objects without official designations in Saturn's rings but excludes other provisional objects which may be clumps of ring material (e.g., S/2004 S3 and S/2004 S4) and excludes 9 other objects detected in rings without official designations.
--Uranus moons 27 27 0 0Titania and Oberon
[discovered 1787]
outer solar system objects, Uranus Trojans 1 0 1 02011 QF99
[discovered 2011]
Objects orbiting the Sun in Uranus' L4 and L5 positions (60 degrees ahead of and behind Uranus, respectively).
comets, short period, non-Jupiter family 109 22 87 0Comets with orbital periods less than 200 years, other than Jupiter family members. Excludes 2 objects with dual designations counted among Centaurs (Chiron and Echeclus).
outer solar system objects, Centaurs 480 162 316 2(2060) Chiron
[discovered 1977]
Outer solar system objects beyond Saturn outside the main Kuiper Belt, generally those crossing within the orbit of Neptune. Sources differ on the division between Centaurs and scattered disk objects.
--Centaur moons 3 2 0 1Phorcys
[discovered 2006]
--Neptune moons 14 14 0 0Triton
[discovered 1846]
outer solar system objects, Neptune Trojans 28 5 23 02001 QR322
[discovered 2001]
Objects orbiting the Sun in Neptune's L4 or L5 positions (60 degrees ahead of or behind Neptune, respectively).
outer solar system objects, Kuiper belt objects 2,717 491 2,199 27(15760) Albion
[discovered 1992]
Objects beyond Neptune in the main Kuiper Belt (generally, 41 to 47 AU from the Sun).
--Kuiper belt object moons 98 13 2 83S/2000 (1998 WW31) 1
[discovered 2000]
Includes satellite of "hst5" observed in 2010.
--Pluto moons 5 5 0 0Charon
[discovered 1978]
The IAU now considers Pluto a dwarf planet.
--Haumea moons 2 2 0 0Namaka
[discovered 2005]
The IAU now considers Haumea a dwarf planet.
--Makemake moons 1 0 1 0S/2015 (136472) 1
[discovered 2015]
The IAU now considers Makemake a dwarf planet.
outer solar system objects, scattered disk objects 584 122 456 6(26181) 1996 GQ21
[discovered 1996]
Outer solar system objects beyond Saturn outside the main Kuiper Belt, generally those orbiting outside the orbit of Neptune. Sources differ on the division between Centaurs and scattered disk objects.
--scattered disk object moons 10 2 0 8
[discovered 2006]
--Eris moons 1 1 0 0Dysnomia
[discovered 2005]
The IAU now considers Eris a dwarf planet.
outer solar system objects, Sednoids 4 2 2 0(90377) Sedna
[discovered 2003]
Objects with perihelia greater than 70 AU.
comets, long-period* 6,036 1 3,2492,786Comets with orbital periods over 200 years. See note below.
comets, ejected 105 0 105 0
[discovered 1885]
Comets previously bound to the solar systems but now ejected (on ultimately hyperbolic orbits).
interstellar objects 2 2 0 01I 'Oumuamua
[discovered 2017]
Objects in the solar system but originating outside the solar system.

* Note: Long-period comets with no official designation include: 2,248 SOHO comets, 87 STEREO comets, 2 other modern comets, and 449 pre-modern comets. The pre-modern comets typically have no computed orbits.

Provisional asteroid and comets numbers do not all represent unique objects (i.e., many provisional objects have been counted more than once in as yet unlinked observations).

As of 28 November 2020, man-made objects in the solar system include an estimated 325 orbiting the Sun, 6 orbiting Venus, 18 orbiting Mars, 1 each orbiting (1) Ceres, Jupiter, and Saturn, and 8 escaping the solar system. This is mentioned here since several objects tracked as minor planets are believed to be spent rocket boosters or other man-made objects: 2010 KQ, 2018 AV2, 2020 SO, and J002E3.

Counts are based primarily on data from: the Minor Planet Center web site; The Catalogue of Cometary Orbits 1999 (Marsden and Williams); The Catalogue of Cometary Orbits 2005 (Marsden and Williams); Cometography, Vol. I (Kronk, 1999); International Comet Quarterly web site; the National Space Science Data Center web site; the Solar and Heliospheric Observatory web site; and the web site for the Asteroid Orbital Elements Database (Bowell) on Lowell Observatory's web site.


© 2001-2019, 2020 by Wm. Robert Johnston.
Last updated 6 December 2020.
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