Largest by diameter

Estimating the sizes of asteroids from observations is difficult due to their irregular shapes, varying albedo, and small angular diameter. Observations by the Very Large Telescope of most large asteroids were published 2019–2021.^[1][2]

More information Name, Picture ...

Name	Picture	Diameter (km) (geometric mean)	Dimensions (km)	Mean distance from Sun (in AU)	Inclination (°)	Date discovered	Discoverer	Class
1 Ceres		939.4±0.2	964.4 × 964.2 × 891.8	2.766	10.6	January 1, 1801	Piazzi, G.	G
4 Vesta		525.4±0.2	572.6 × 557.2 × 446.4 ± 0.2	2.362	7.14	March 29, 1807	Olbers, H. W.	V
2 Pallas		511±4[1]	568×530×450	2.773	34.9	March 28, 1802	Olbers, H. W.	B
10 Hygiea		433±8[1]	450×430×424	3.139	5.1	April 12, 1849	de Gasparis, A.	C
704 Interamnia		332±5[1]	362×348×310	3.062	17.3	October 2, 1910	Cerulli, V.	F
52 Europa		319±4[1]	378×336×255	3.095	7.48	February 4, 1858	Goldschmidt, H.	C
511 Davida		298±4[1]	359×293×253	3.168	15.9	May 30, 1903	Dugan, R. S.	C
87 Sylvia		271±5[1]	363×249×191 or 374×248×194	3.485	10.9	May 16, 1866	Pogson, N. R.	X
15 Eunomia		270±3[1]	357×255×212	2.643	11.75	July 29, 1851	de Gasparis, A.	S
31 Euphrosyne		268±4[1]	294×280×248	3.149	26.3	September 1, 1854	Ferguson, J.	C
65 Cybele		263±3	297 × 291 × 213	3.439	3.56	March 8, 1861	Tempel, E. W.	C
624 Hektor		256±12 (if bilobe)	403 × 201	5.235	18.66	February 10, 1907	Kopff, A.	D
3 Juno		254±2[1]	288×250×225	2.672	12.98	September 1, 1804	Harding, K. L.	S
451 Patientia		254±3		3.059	15.2	December 4, 1899	Charlois, A.
107 Camilla		254±12[3]		3.476	10	November 17, 1868	Pogson, N. R.	C
324 Bamberga		227±3[1]	234×224×225	2.684	11.1	February 25, 1892	Palisa, J.	C
16 Psyche		223±3[1]	279×232×189 ± 10%	2.924	3.1	March 17, 1852	de Gasparis, A.	M
88 Thisbe		218±3[1]	255×232×193	2.769	5.22	June 15, 1866	Peters, C. H. F.	B
48 Doris		215±3[1]	257×211×185	3.108	6.55	September 19, 1857	Goldschmidt, H.	C
19 Fortuna		211±2[1]	225×205×195	2.442	1.57	August 22, 1852	Hind, J. R.	G
121 Hermione		209±5?[4]		3.457	7.6	May 12, 1872	Watson, J. C.	C
24 Themis		208±3[1]	232×220×176	3.136	0.76	April 5, 1853	de Gasparis, A.	C
94 Aurora		205±4 ? (< 200 km)[1]	225×173	3.160	7.97	September 6, 1867	Watson, J. C.	C
29 Amphitrite		204±2[1]	222×209×183	2.554	6.08	March 1, 1854	Marth, A.	S
13 Egeria		202±3[1]	238×199×182	2.576	16.54	November 2, 1850	de Gasparis, A.	G
130 Elektra		199±2[1]	262×205×164	3.127	22.78	February 17, 1873	C. H. F. Peters	C
7 Iris		199±10[1]	268×234×180[5]	2.386	5.52	August 13, 1847	Hind, J. R.	S
6 Hebe		195±3[1]	205x185x170	2.426	14.75	July 1, 1847	Hencke, K. L.	S
375 Ursula		192±4		3.126	15.94	September 18, 1893	Charlois, A.	C
702 Alauda		191±2		3.195	20.59	July 16, 1910	Helffrich, J.	C/B
45 Eugenia		188±2[1]	252×191×138	2.720	6.61	June 27, 1857	Goldschmidt, H.	F
41 Daphne		187±13[1]	235×183×153	2.765	15.77	May 22, 1856	Goldschmidt, H.	C
423 Diotima		176±4		3.065	11.23	December 7, 1896	Charlois, A.	C
259 Aletheia		174±1		3.135	10.81	June 28, 1886	Peters, C. H. F.	C/P/X
372 Palma		174±3		3.149	23.83	August 19, 1893	Charlois, A.	B
9 Metis		173±2[1]	222×182×130	2.385	5.58	April 25, 1848	Graham, A.	S
532 Herculina		168±1		2.772	16.31	April 20, 1904	Wolf, M.	S
354 Eleonora		165±3[1]	191×162×144	2.798	18.4	January 17, 1893	Auguste Charlois	S
128 Nemesis		163±5[1]	178×163×147	2.751	6.25	November 25, 1872	Watson, J. C.	C
(4:1 resonance) [sort by 'Mean Distance from Sun' to place in table]				2.06	(defines inner edge of main belt)
(3:1 resonance)				2.50	(separates inner from middle belt)
(5:2 resonance)				2.82	(separates middle from outer belt)
(7:3 resonance)				2.95
(2:1 resonance)				3.27	(defines outermost belt)
(1:1 resonance)				5.20	(Trojan asteroids – defines outer edge of main belt)

Close

The number of bodies grows rapidly as the size decreases. Based on IRAS data there are about 140 main-belt asteroids with a diameter greater than 120 km,^[6] which is approximately the transition point between surviving primordial asteroids and fragments thereof.^[7][8] For a more complete list, see List of Solar System objects by size.

The inner asteroid belt (defined as the region interior to the 3:1 Kirkwood gap at 2.50 AU) has few large asteroids. Of those in the above list, only 4 Vesta, 19 Fortuna, 6 Hebe, 7 Iris and 9 Metis orbit there. (Sort table by mean distance.)

Most massive

Below are the sixteen most-massive measured asteroids.^[9] Ceres, at a third the estimated mass of the asteroid belt, is half again as massive as the next fifteen put together. The masses of asteroids are estimated from perturbations they induce on the orbits of other asteroids, except for asteroids that have been visited by spacecraft or have an observable moon, where a direct mass calculation is possible. Different sets of astrometric observations lead to different mass determinations; the biggest problem is accounting for the aggregate perturbations caused by all of the smaller asteroids.^[10]

Graphs are unavailable due to technical issues. There is more info on Phabricator and on MediaWiki.org.

Comparative masses of the asteroids with nominal masses > 20×10¹⁸ kg, assuming a total Main Belt mass of 2394×10¹⁸ kg. The mass of Herculina is particularly uncertain.

The proportions assume that the total mass of the asteroid belt is 2.39×10²¹ kg, or (12.4±1.0)×10⁻¹⁰ M_☉.^[12]

Outside the top four, the ranking of all the asteroids is uncertain, as there is a great deal of overlap among the estimates.

The largest asteroids with an accurately measured mass, because they have been studied by the probe Dawn, are 1 Ceres with a mass of (939.3±0.5)×10¹⁸ kg, and 4 Vesta at (259.076±0.001)×10¹⁸ kg. The third-largest asteroid with an accurately measured mass, because it has moons, is 87 Sylvia at (14.76±0.06)×10¹⁸ kg. Other large asteroids with masses measured from their moons are 107 Camilla and 130 Elektra.^[3][13][1]

For a more complete list, see List of Solar System objects by size. Other large asteroids such as 423 Diotima currently only have estimated masses.^[14][15]

Brightest from Earth

Only Vesta is regularly bright enough to be seen with the naked eye. Under ideal viewing conditions with very dark skies, a keen eye might be able to also see Ceres, as well as Pallas and Iris at their rare perihelic oppositions.^[16] The following asteroids can all reach an apparent magnitude brighter than or equal to the +8.3 attained by Saturn's moon Titan at its brightest, which was discovered 145 years before the first asteroid was found owing to its closeness to the easily observed Saturn.

None of the asteroids in the outer part of the asteroid belt can ever attain this brightness. Even Hygiea and Interamnia rarely reach magnitudes of above 10.0. This is due to the different distributions of spectral types within different sections of the asteroid belt: the highest-albedo asteroids are all concentrated closer to the orbit of Mars, and much lower albedo C and D types are common in the outer belt.

Those asteroids with very high eccentricities will only reach their maximum magnitude rarely, when their perihelion is very close to a heliocentric conjunction with Earth, or (in the case of 99942 Apophis, (152680) 1998 KJ9, (153814) 2001 WN5, and 367943 Duende) when the asteroid passes very close to Earth.

* Apophis will only achieve that brightness on April 13, 2029.^[17][18] It typically has an apparent magnitude of 20–22.

Slowest rotators

This list contains the slowest-rotating known minor planets with a period of at least 1000 hours, or 412⁄3 days, while most bodies have rotation periods between 2 and 20 hours. Also see Potentially slow rotators for minor planets with an insufficiently accurate period (U < 2).

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Fastest rotators

This list contains the fastest-rotating minor planets with a period of less than 100 seconds, or 0.0277 hours. Bodies with a highly uncertain period, having a quality of less than 2, are highlighted in dark-grey. The fastest rotating bodies are all unnumbered near-Earth objects (NEOs) with a diameter of less than 100 meters (see table).

Among the numbered minor planets with an unambiguous period solution are (459872) 2014 EK24, a 60-meter sized stony NEO with a period of 352 seconds, as well as (335433) 2005 UW163 and (60716) 2000 GD65, two main-belt asteroids, with a diameter of 0.86 and 2.25 kilometers and a period of 1.29 and 1.95 hours, respectively (see full list).

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Retrograde

Minor planets with orbital inclinations greater than 90° (the greatest possible is 180°) orbit in a retrograde direction. As of March 2018^[update], of the near-800,000 minor planets known, there are only 99 known retrograde minor planets (0.01% of total minor planets known).^[19] In comparison, there are over 2,000 comets with retrograde orbits. This makes retrograde minor planets the rarest group of all. High-inclination asteroids are either Mars-crossers (possibly in the process of being ejected from the Solar System) or damocloids. Some of these are temporarily captured in retrograde resonance with the gas giants.^[20]

^ the value given when the number of observations is multiplied by the observation arc; larger values are generally better than smaller values depending on residuals.

Highly inclined

Trojans

• Earth trojans: 2010 TK7 and (614689) 2020 XL5.
• Mars trojans: (121514) 1999 UJ7, 5261 Eureka, (101429) 1998 VF31, (311999) 2007 NS2, (385250) 2001 DH47, 2011 SC191, 2011 UN63, and the candidate 2011 SL25.
• Jupiter trojans: the first one was discovered in 1906, 588 Achilles, and the current total is over 6,000.

Record-setting close approaches to Earth

Spacecraft targets

Surface resolved by telescope or lightcurve

Multiple systems resolved by telescope

• 90 Antiope

Comet-like activity

• 2006 VW139
• P/2013 P5

Disintegration

• 6478 Gault
• P/2013 R3

Landmark asteroids

Numbered minor planets that are also comets

The above table lists only numbered asteroids that are also comets. Note there are several cases where a non-numbered minor planets turned out to be a comet, e.g. C/2001 OG108 (LONEOS), which was provisionally designated 2001 OG₁₀₈.

Minor planets that were misnamed and renamed

In earlier times, before the modern numbering and naming rules were in effect, asteroids were sometimes given numbers and names before their orbits were precisely known. And in a few cases duplicate names were given to the same object (with modern use of computers to calculate and compare orbits with old recorded positions, this type of error no longer occurs). This led to a few cases where asteroids had to be renamed.^[26]

Landmark names

Asteroids were originally named after female mythological figures. Over time the rules loosened.

First asteroid with non-Classical and non-Latinized name: 64 Angelina (in honor of a research station)

First asteroid with a non-feminine name: 139 Juewa (ambiguous) or 141 Lumen

First asteroid with a non-feminized man's name: 903 Nealley

Lowest-numbered unnamed asteroid (As of 2021^[update]): (4596) 1981 QB