Known populations of solar system objects: 30 August 2021

compiled by Wm. Robert Johnston
last updated 1 September 2021

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

Summary

Star: 1

Planets*: 8
Dwarf planets*: 5 (5 named)
Asteroids*: 1,112,918 (585,075 numbered, 527,843 provisional)
Outer solar system objects*: 3,893 (882 numbered, 3,011 provisional, 34 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 (182 numbered, 23 provisional, 3 without official designations)
Moons of dwarf planets: 9 (8 numbered, 1 provisional)
Moons of asteroids: 323 (17 numbered, 19 provisional, 287 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: 1,124,474 (586,591 with permanent designations, 534,715 with provisional designations, 3,202 without official designations)

Objects with names:
--1 star, 8 planets, 5 dwarf planets, 22,614 asteroids, 52 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 here 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
disc.
notes
star 1 1 0 0Sun
planets 8 8 0 0Earth As currently defined by IAU.
dwarf planets 5 5 0 0(1) Ceres 1801As currently defined by IAU.
--Mercury moons 0 0 0 0(none)
asteroids, Atira 50 9 41 0(163693) Atira 2003Asteroids with orbits entirely inside the Earth's orbit.
--Atira asteroid moons 1 0 0 1(no designation) 2017
--Venus moons 0 0 0 0(none)
asteroids, Aten 2,063 243 1,820 0(2062) Aten 1976Asteroids with semimajor axes less than 1.0 AU.
--Aten asteroid moons 7 1 0 6(no designation) 1999
--Earth moons 1 1 0 0Moon
asteroids, Earth Trojans 1 0 1 02010 TK7 2010Asteroid 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 13,482 1,419 12,063 0(1862) Apollo 1932Asteroids (other than Atens and Earth trojans) crossing the Earth's orbit.
--Apollo asteroid moons 49 1 3 45(no designation) 1997
asteroids, Amor 11,067 1,269 9,798 0(433) Eros 1898Asteroids (other than Aitras, Atens, Apollos, or Earth trojans) with perihelion distances less than 1.3 AU.
--Amor asteroid moons 27 0 0 27(no designation) 1997
--Mars moons 2 2 0 0Phobos 1877
asteroids, Mars Trojans 9 5 4 0(5261) Eureka 1990Asteroids 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(no designation) 2014
asteroids, Mars crossers 18,512 4,776 13,736 0(132) Aethra 1873Asteroids (other than Atiras, Atens, Apollos, or Mars trojans) crossing Mars' orbit.
--Mars crosser asteroid moons 31 0 1 30(no designation) 2014
asteroids, main belt 1,056,560571,877484,683 0(2) Pallas 1802Asteroids not counted elsewhere (some may cross the orbits of Mars or Jupiter). Excludes (1) Ceres which is declared a dwarf planet by the IAU.
--main belt asteroid moons 201 12 15 174Dacytl 1993
--Ceres moons 0 0 0 0(none)
comets, Jupiter family 746 371 375 0 Comets 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 1610Does not include 57 objects without computed orbits.
asteroids, Jupiter Trojans 10,615 5,455 5,160 0(588) Achilles 1906Asteroids orbiting the Sun in Jupiter's L4 and L5 positions (60 degrees ahead of and behind Jupiter, respectively).
--Jupiter Trojan asteroid moons 6 3 0 3Menoetius 2001
asteroids, other unusual 559 22 537 0(944) Hidalgo 1920Asteroids with aphelion distances greater than 7.5 AU, other than those in other categories.
--Saturn moons 85 66 16 3Titan 1655Includes 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 1787
outer solar system objects, Uranus Trojans 1 0 1 02011 QF99 2011Objects 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 0 Comets 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 496 194 302 2(2060) Chiron 1977Outer 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 2 2 0 0Phorcys 2006
--Neptune moons 14 14 0 0Triton 1846
outer solar system objects, Neptune Trojans 28 5 23 02001 QR322 2001Objects 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 2,746 535 2,211 27(15760) Albion 1992Objects beyond Neptune in the main Kuiper Belt (generally, 41 to 47 AU from the Sun).
--Kuiper belt object moons 101 13 2 86S/2000 (1998 WW31) 1 2000Includes satellite of "hst5" observed in 2010.
--Pluto moons 5 5 0 0Charon 1978The IAU now considers Pluto a dwarf planet.
--Haumea moons 2 2 0 0Namaka 2005The IAU now considers Haumea a dwarf planet.
--Makemake moons 1 0 1 0S/2015 (136472) 1 2015The IAU now considers Makemake a dwarf planet.
outer solar system objects, scattered disk objects 618 146 472 5(26181) 1996 GQ21 1996Outer 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 8 2 0 6(no designation) 2006
--Eris moons 1 1 0 0Dysnomia 2005The IAU now considers Eris a dwarf planet.
outer solar system objects, Sednoids 4 2 2 0(90377) Sedna 2003Objects with perihelia greater than 70 AU.
comets, long-period* 6,036 1 3,2492,786 Comets with orbital periods over 200 years. See note below.
comets, ejected 105 0 105 0 1885Comets previously bound to the solar systems but now ejected (on ultimately hyperbolic orbits).
interstellar objects 2 2 0 01I 'Oumuamua 2017Objects in the solar system but originating outside the solar system.
type of objecttotalpermanent designationprovisional designationno official designationfirst one
discovered
year
disc.
notes

* 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).

Comet counts are as of November 2020.

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.


© 2001-2020, 2021 by Wm. Robert Johnston.
Last updated 1 September 2021.
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