For related historical graphs see Historical known populations of solar system objects.
Dwarf planets*: 5 (5 named)
Asteroids*: 850,018 (541,391 numbered, 308,627 provisional)
Outer solar system objects*: 3,577 (772 numbered, 2,771 provisional, 34 without official designations)
Comets**: 6,746 (386 numbered**, 3,653 with provisional designations, 2,707 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: 291 (13 numbered, 20 provisional, 258 without official designations)
Moons of outer solar system objects: 104 (15 numbered, 2 provisional, 87 without official designations)
Objects with ring systems: 6 (4 planets, 1 dwarf planet, 1 Centaur)
Total objects: 860,969 (542,770 with permanent designations, 315,110 with provisional designations, 3,089 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, 13 asteroid moons, 15 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 27 December 2019 with these exceptions: outer solar system objecs (23 December 2019).
* 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) 2007 OR10, 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 five objects with dual designations counted among numbered asteroids.
Known populations of solar system objects--detail
|type of object||total||permanent designation||provisional designation||no official designation||first one discovered|
|planets||8||8||0||0||Earth||As currently defined by IAU.|
|dwarf planets||5||5||0||0||(1) Ceres |
|As currently defined by IAU.|
|asteroids, Aten||1,642||243||1,399||0||(2062) Aten |
|Asteroids with semimajor axes less than 1.0 AU.|
|--Aten asteroid moons||8||1||0||7|| |
|asteroids, Earth Trojans||1||0||1||0||2010 TK7 |
|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||10,898||1,409||9,489||0||(1862) Apollo |
|Asteroids (other than Amors) crossing the Earth's orbit.|
|--Apollo asteroid moons||47||0||3||44|| |
|asteroids, Amor||9,129||1,263||7,866||0||(433) Eros |
|Asteroids (other than Amors or Apollos) with perihelion distances less than 1.3 AU.|
|--Amor asteroid moons||21||0||0||21|| |
|--Mars moons||2||2||0||0||Phobos |
|asteroids, Mars Trojans||9||5||4||0||(5261) Eureka |
|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|| |
|asteroids, main belt||821,028||533,557||287,471||0|
|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||209||10||17||182||Dacytl |
|comets, Jupiter family||724||362||362||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||0||Io, Europa, Ganymede, and Callisto |
|Does not include 7 objects observed near Amalthea in 2002.|
|asteroids, Jupiter Trojans||7,311||4,914||2,397||0||(588) Achilles |
|Asteroids orbiting the Sun in Jupiter's L4 and L5 positions (60 degrees ahead of and behind Jupiter, respectively).|
|--Jupiter Trojan asteroid moons||5||2||0||3||Menoetius |
|--Saturn moons||85||53||29||3||Titan |
|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||0||Titania and Oberon |
|outer solar system objects, Uranus Trojans||1||0||1||0||2011 QF99 |
|Objects orbiting the Sun in Uranus' L4 and L5 positions (60 degrees ahead of and behind Uranus, respectively).|
|comets, short period, non-Jupiter family||111||23||88||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||436||158||276||2||(2060) Chiron |
|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||1||Phorcys |
|--Neptune moons||14||14||0||0||Triton |
|outer solar system objects, Neptune Trojans||23||5||18||0||2001 QR322 |
|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||2,577||481||2,069||27||(15760) Albion |
|Objects beyond Neptune in the main Kuiper Belt (generally, 41 to 47 AU from the Sun).|
|--Kuiper belt object moons||72||12||2||58||S/2000 (1998 WW31) 1 |
|Includes satellite of "hst5" observed in 2010.|
|--Pluto moons||5||5||0||0||Charon |
|The IAU now considers Pluto a dwarf planet.|
|--Haumea moons||2||2||0||0||Namaka |
|The IAU now considers Haumea a dwarf planet.|
|--Makemake moons||1||0||1||0||S/2015 (136472) 1 |
|The IAU now considers Makemake a dwarf planet.|
|outer solar system objects, scattered disk objects||952||284||662||6||(26181) 1996 GQ21 |
|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||12||3||0||9|| |
|--Eris moons||1||1||0||0||Dysnomia |
|The IAU now considers Eris a dwarf planet.|
|outer solar system objects, Sednoids||4||1||3||0||(90377) Sedna |
|Objects with perihelia greater than 70 AU.|
|comets, long-period*||5,911||1||3,203||2,707||Comets with orbital periods over 200 years. See note below.|
|interstellar objects||2||2||0||0||1I 'Oumuamua |
|Objects in the solar system but originating outside the solar system.|
* Note: Long-period comets with no official designation include: 2,092 SOHO comets, 89 STEREO comets, 70 other modern comets, and 456 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 February 2019, an estimated 229 man-made objects were orbiting the Sun, 7 orbiting Venus, 17 orbiting Mars, 1 orbiting (1) Ceres, 1 was near (162173) Ryugu, 1 was orbiting Jupiter, and 8 are escaping the solar system. This is mentioned since at least one Apollo "asteroid" with a provisional designation--2010 KQ--may be a spent rocket booster.
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 1 January 2020.
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