The ten biggest bodies in the asteroid belt, ranked by mean diameter from spacecraft, adaptive-optics imaging, and stellar occultation data.
Quick answer: 1. 1 Ceres, 2. 4 Vesta, 3. 2 Pallas, 4. 10 Hygiea, 5. 704 Interamnia, 6. 52 Europa, 7. 511 Davida, 8. 87 Sylvia, 9. 15 Eunomia, 10. 31 Euphrosyne.
The asteroid belt holds millions of rocky bodies, but its mass is dominated by a handful of giants. This list ranks the ten largest by mean (volume-equivalent) diameter, drawing on the best available measurements: NASA's Dawn spacecraft visited the two biggest true asteroids up close, while the European Southern Observatory's VLT/SPHERE instrument and stellar occultation timings pin down the rest. At the top sits 1 Ceres, so large the IAU reclassified it as a dwarf planet in 2006, though it remains the biggest object in the belt by origin and location. After Ceres, Vesta and Pallas complete the "big three," and there is a sharp size cliff below the top four, where diameters tumble from the 400-500 km range down toward roughly 270 km. If you want a sense of scale for the solar system's leftover building blocks, this is the roster.
The largest object in the asteroid belt at 939.4 km across. The IAU reclassified it as a dwarf planet in 2006, but by origin and location it is still the belt's biggest body; NASA's Dawn orbiter confirmed its diameter in 2015.
The most massive true asteroid and the largest body that formed within the belt. Its triaxial shape spans 572.6 x 557.2 x 446.4 km, for a mean diameter of 525.4 km measured by NASA's Dawn spacecraft in 2011-2012.
The third-largest asteroid, now understood to be slightly smaller than Vesta, with a mean diameter of 511 km from VLT/SPHERE adaptive-optics imaging. Its steeply inclined orbit makes it difficult for spacecraft to reach.
The fourth-largest asteroid and the biggest of the carbonaceous C-type bodies. 2019 VLT/SPHERE imaging showed it to be nearly spherical at 433 km, making it a candidate dwarf planet.
A sharp drop in size from the big four. This dark F-type asteroid is fifth-largest at 332 km, measured by VLT/SPHERE.
A large C-type asteroid, sixth-largest at 319 km by volume-equivalent diameter. Not to be confused with Jupiter's icy moon of the same name.
One of the larger C-type asteroids, seventh-largest at 298 km. VLT/SPHERE imaging revealed an irregular, lumpy shape.
An elongated X-type asteroid, eighth-largest at 271 km. It is famous as the first known triple asteroid system, orbited by two moons named Romulus and Remus.
The largest of the stony S-type asteroids and ninth-largest overall at 270 km. VLT/SPHERE imaging shows an elongated body.
A dark C-type asteroid rounding out the top ten at 268 km. It sits in a highly inclined orbit and is the namesake of a major asteroid family.
| # | Name | discovered | class | measurement |
|---|---|---|---|---|
| 1 | 1 Ceres | 1801 | Dwarf planet (largest asteroid-belt body) | Dawn spacecraft / VLT-SPHERE |
| 2 | 4 Vesta | 1807 | Asteroid (largest true asteroid) | Dawn spacecraft |
| 3 | 2 Pallas | 1802 | Asteroid | VLT-SPHERE imaging |
| 4 | 10 Hygiea | 1849 | Asteroid (possible dwarf planet) | VLT-SPHERE imaging |
| 5 | 704 Interamnia | 1910 | Asteroid | VLT-SPHERE imaging |
| 6 | 52 Europa | 1858 | Asteroid | VLT-SPHERE imaging |
| 7 | 511 Davida | 1903 | Asteroid | VLT-SPHERE imaging |
| 8 | 87 Sylvia | 1866 | Asteroid (triple system) | VLT-SPHERE imaging |
| 9 | 15 Eunomia | 1851 | Asteroid | VLT-SPHERE imaging |
| 10 | 31 Euphrosyne | 1854 | Asteroid | VLT-SPHERE imaging |
Bodies are ranked by mean (volume-equivalent) diameter in kilometers, largest to smallest. Diameters come from the most authoritative source available for each object: in-situ spacecraft measurement (NASA's Dawn orbiter for Ceres and Vesta), VLT/SPHERE adaptive-optics imaging from the European Southern Observatory, or stellar occultation timings, as compiled in the primary astronomical literature. Inclusion criterion: minor-planet bodies of the asteroid belt. 1 Ceres is included as the largest belt body despite its 2006 IAU reclassification as a dwarf planet; every other entry is a formally classified asteroid. Where a body is triaxial or irregular, the volume-equivalent mean diameter is used so entries are compared on a consistent basis.
1 Ceres is the largest body in the asteroid belt at 939.4 km in diameter. The IAU reclassified it as a dwarf planet in 2006, so the largest object still formally classified as an asteroid is 4 Vesta at 525.4 km.
Both, depending on how you frame it. Ceres formed in and orbits within the asteroid belt, which is why it is often listed as the largest asteroid, but in 2006 the IAU reclassified it as a dwarf planet because its gravity pulled it into a round shape.
The most precise figures come from spacecraft that fly by or orbit an asteroid, like NASA's Dawn mission to Ceres and Vesta. For bodies no spacecraft has visited, astronomers use adaptive-optics imaging (such as the VLT/SPHERE instrument) or time how a star's light blinks out as an asteroid passes in front of it, a technique called stellar occultation.
The four largest bodies, Ceres, Vesta, Pallas, and Hygiea, account for roughly 62% of the total mass of the asteroid belt, with Ceres alone making up about 39%. Below them there is a sharp drop in size, with the fifth-largest, Interamnia, measuring only about 332 km versus Hygiea's 433 km.