Largest By Diameter
Estimating the sizes of asteroids from observations is difficult due to their irregular shapes, varying albedo (reflectivity), and small angular diameter. For example pure C-type asteroids are much darker than most. Asteroids with only one or two axes measured may have a falsely inflated geometric mean diameter if the unknown second and/or third axis is noticeably smaller than the primary axis. Asteroid 16 Psyche has an IRAS diameter of 253 km, yet has a more recent and accurate geometric mean of only 186 km.
| Name | Diameter (km) (geometric mean) |
Dimensions (km) | Mean Distance from Sun (in AU) |
Date Discovered | Discoverer | Class |
|---|---|---|---|---|---|---|
| Ceres, 11 Ceres | 952 | 975×975×909 | 2.766 | 01801-01-01January 1, 1801 | Piazzi, G. | G |
| Pallas, 22 Pallas | 544 | 582×556×500 | 2.773 | 01802-03-28March 28, 1802 | Olbers, H. W. | B |
| Vesta, 44 Vesta | 525.4 | 572.6×557.2×446.4 | 2.362 | 01807-03-29March 29, 1807 | Olbers, H. W. | V |
| Hygiea, 1010 Hygiea | 431 | 530×407×370 | 3.139 | 01849-04-12April 12, 1849 | de Gasparis, A. | C |
| Interamnia, 704704 Interamnia | 326 | 350×304 | 3.062 | 01910-10-02October 2, 1910 | Cerulli, V. | F |
| Europa, 5252 Europa | 301 | 360×315×240 | 3.095 | 01858-02-04February 4, 1858 | Goldschmidt, H. | C |
| Davida, 511511 Davida | 289 | 357×294×231 | 3.168 | 01903-05-30May 30, 1903 | Dugan, R. S. | C |
| Sylvia, 8787 Sylvia | 286 | 385×265×230 | 3.485 | 01866-05-16May 16, 1866 | Pogson, N. R. | X |
| Cybele, 6565 Cybele | 273 | 302×290×232 | 3.439 | 01861-03-08March 8, 1861 | Tempel, E. W. | C |
| Eunomia, 1515 Eunomia | 268 | 357×255×212 | 2.643 | 01851-07-29July 29, 1851 | de Gasparis, A. | S |
| Juno, 33 Juno | 258 | 320×267×200 | 2.672 | 01804-09-01September 1, 1804 | Harding, K. L. | S |
| Euphrosyne, 3131 Euphrosyne | 256 | 3.149 | 01854-09-01September 1, 1854 | Ferguson, J. | C | |
| Hektor, 624624 Hektor | 241 | 370×195(×195) | 5.235 | 01854-02-10February 10, 1854 | Kopff, A. | D |
| Thisbe, 8888 Thisbe | 232 | 221×201×168 | 2.769 | 01866-06-15June 15, 1866 | Peters, C. H. F. | B |
| Bamberga, 324324 Bamberga | 229 | 2.684 | 01892-02-25February 25, 1892 | Palisa, J. | C | |
| Patientia, 451451 Patientia | 225 | 3.059 | 01899-12-04December 4, 1899 | Charlois, A. | ||
| Herculina, 532532 Herculina | 222 | 2.772 | 01904-04-20April 20, 1904 | Wolf, M. | S | |
| Doris, 4848 Doris | 222 | 278×142 | 3.108 | 01857-09-19September 19, 1857 | Goldschmidt, H. | C |
| Ursula, 375375 Ursula | 216 | 3.126 | 01893-09-18September 18, 1893 | Charlois, A. | ||
| Camilla, 107107 Camilla | 215 | 285×205×170 | 3.476 | 01868-11-17November 17, 1868 | Pogson, N. R. | C |
| Eugenia, 4545 Eugenia | 213 | 305×220×145 | 2.720 | 01857-06-27June 27, 1857 | Goldschmidt, H. | F |
| Iris, 77 Iris | 213 | 240×200×200 | 2.386 | 01847-08-13August 13, 1847 | Hind, J. R. | S |
| Amphitrite, 2929 Amphitrite | 212 | 233×212×193 | 2.554 | 01854-03-01March 1, 1854 | Marth, A. | S |
| Diotima, 423423 Diotima | 209 | 171×138 | 3.065 | 01896-12-07December 7, 1896 | Charlois, A. | C |
| Fortuna, 1919 Fortuna | 208 | 225×205×195 | 2.442 | 01852-08-22August 22, 1852 | Hind, J. R. | G |
| Egeria, 1313 Egeria | 206 | 217×196 | 2.576 | 01850-11-02November 2, 1850 | de Gasparis, A. | G |
| Themis, 2424 Themis | 198 | 3.136 | 01853-04-05April 5, 1853 | Gasparis, A. | C | |
| Aurora, 9494 Aurora | 197 | 225×173 | 3.160 | 01867-09-06September 6, 1867 | Watson, J. C. | C |
| Alauda, 702702 Alauda | 195 | 3.195 | 01910-07-16July 16, 1910 | Helffrich, J. | ||
| Hermione, 121121 Hermione | 190 | 268×186×183 | 3.457 | 01872-05-12May 12, 1872 | Watson, J. C. | C |
| Palma, 372372 Palma | 189 | 3.149 | 01893-08-19August 19, 1893 | Charlois, A. | ||
| Nemesis, 128128 Nemesis | 188 | 2.751 | 01872-11-25November 25, 1872 | Watson, J.C. | C | |
| Hebe, 66 Hebe | 186 | 205x185x170 | 2.426 | 01847-07-01July 1, 1847 | Hencke, K.L. | S |
| Psyche, 1616 Psyche | 186 | 240×185×145 | 2.924 | 01852-03-17March 17, 1852 | de Gasparis, A. | M |
| Lachesis, 120120 Lachesis | 174 | 3.301 | 01872-04-10April 10, 1872 | Borrelly, A. | C | |
| Daphne, 4141 Daphne | 174 | 213x160 | 3.517 | 01856-05-22May 22, 1856 | Goldschmidt, H. | C |
| Metis, 99 Metis | 174 | 222x182x130 | 2.385 | 01848-04-25April 25, 1848 | Graham, A. | S |
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. 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, and 7 Iris orbit there.
Read more about this topic: List Of Notable Asteroids
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