Known populations of solar system objects: July 2019

compiled by Wm. Robert Johnston
last updated 13 July 2019

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

Summary

Star: 1

Planets*: 8
Dwarf planets*: 5 (5 named)
Asteroids*: 792,087 (540,352 numbered [of which 21,878 are named], 251,735 provisional)
Outer solar system objects*: 3,557 (771 numbered [of which 44 are named], 2,753 provisional, 33 without official designations)
Comets**: 6,619 (373 numbered**, 3,643 with provisional designations, 2,603 without official designations)

Interstellar objects: 1 (1 numbered)

Moons of planets: 185 (169 numbered [of which 149 are named], 16 provisional)
Moons of dwarf planets: 9 (8 named, 1 provisional)

Moons of asteroids: 283 (12 named, 21 provisional, 250 without official designations)
Moons of outer solar system objects: 84 (15 named, 2 provisional, 67 without official designations)

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

Total objects: 802,839 (541,666 with permanent designations, 258,138 with provisional designations, 2,953 without official designations)

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 5 June 2019 with these exceptions: main belt asteroids with provisional designations (18 May 2019); comets (13 July 2019); moons (13 July 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 objecttotalpermanent designationprovisional designationno official designationfirst one discovered
[year]
notes
star 1 1 0 0Sun
planets 8 8 0 0EarthAs currently defined by IAU.
dwarf planets 5 5 0 0(1) Ceres
[1801]
As currently defined by IAU.
--Mercury moons 0 0 0 0(none)
--Venus moons 0 0 0 0(none)
asteroids, Aten 1,538 243 1,295 0(2062) Aten
[1976]
Asteroids with semimajor axes less than 1.0 AU.
--Aten asteroid moons 8 0 0 8
[1999]
--Earth moons 1 1 0 0Moon
asteroids, Earth Trojans 1 0 1 02010 TK7
[2010]
Asteroid orbiting in horseshoe orbits with the Earth. Does not include non-Trojan coorbital objects, such as 2002 AA29.
asteroids, Apollo 10,151 1,407 8,744 0(1862) Apollo
[1932]
Asteroids (other than Amors) with perihelion distances less than 1.0 AU.
--Apollo asteroid moons 46 0 3 43
[1997]
asteroids, Amor 8,538 1,265 7,273 0(433) Eros
[1898]
Asteroids (other than Amors or Apollos) with perihelion distances less than 1.3 AU.
--Amor asteroid moons 21 0 0 21
[1997]
--Mars moons 2 2 0 0Phobos
[1877]
asteroids, Mars Trojans 9 5 4 0(5261) Eureka
[1990]
Asteroids orbiting in Mars' L4 and L5 positions (60 degrees ahead of and behind Mars, respectively).
--Mars Trojan asteroid moons 1 0 0 1
[2014]
asteroids, main belt 764,770532,518232,252 0
(2) Pallas [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.
--Ceres moons 0 0 0 0(none)
--main belt asteroid moons 202 10 18 174Dacytl
[1993]
comets, Jupiter family 718 350 368 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
[1610]
Does not include 7 objects observed near Amalthea in 2002.
asteroids, Jupiter Trojans 7,079 4,914 2,165 0(588) Achilles
[1906]
Asteroids orbiting in Jupiter's L4 and L5 positions (60 degrees ahead of and behind Jupiter, respectively).
--Jupiter Trojan asteroid moons 5 2 0 3Menoetius
[2001]
--Saturn moons 62 53 9 0Titan
[1655]
Includes S/2004 S6 but excludes other provisional objects which may be clumps of ring material (e.g., S/2004 S3 and S/2004 S4) and excludes 12 objects detected in rings without official designations.
--Uranus moons 27 27 0 0Titania and Oberon
[1787]
asteroids, Uranus Trojans 1 0 1 02011 QF99
[2011]
Asteroids orbiting 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).
--Neptune moons 14 14 0 0Triton
[1846]
KBOs, Neptune Trojans 23 5 18 02001 QR322
[2001]
Outer solar system objects orbiting in Neptune's L4 or L5 positions (60 degrees ahead of or behind Neptune, respectively).
Centaurs, scattered disk objects 952 284 662 6(2060) Chiron
[1977]
Outer solar system objects beyond Saturn outside the main Kuiper Belt. Centaurs and scattered disk objects are included together since different delineations between the two categories exist.
--Centaur/scattered disk object moons 12 3 0 9
[2002]
Kuiper Belt objects 2,577 481 2,069 27(15760) Albion
[1992]
Outer solar system objects beyond Neptune in the main Kuiper Belt.
--Kuiper Belt object moons 72 12 2 58S/2000 (1998 WW31) 1
[2000]
Includes satellite of "hst5" observed in 2010.
--Pluto moons 5 5 0 0Charon
[1978]
The IAU now considers Pluto a dwarf planet.
--Haumea moons 2 2 0 0Namaka
[2005]
The IAU now considers Haumea a dwarf planet.
--Makemake moons 1 0 1 0S/2015 (136472) 1
[2015]
The IAU now considers Makemake a dwarf planet.
--Eris moons 1 1 0 0Dysnomia
[2005]
The IAU now considers Eris a dwarf planet.
Sednoids 4 1 3 0(90377) Sedna
[2003]
Outer solar system objects with perihelia greater than 70 AU.
comets, long-period* 5,792 1 3,1882,603Comets with orbital periods over 200 years. See note below.
interstellar objects 1 1 0 01I 'Oumuamua
[2017]
Objects in the solar system but originating outside the solar system.

* Note: Long-period comets with no official designation include: 1,988 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.


© 2001-2018, 2019 by Wm. Robert Johnston.
Last updated 13 July 2019.
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