Asteroid
The dwarf planet Ceres is by far the largest asteroid, with a diameter of . The next largest are 4 Vesta and 2 Pallas, both with diameters of just over . Vesta is the only main-belt asteroid that can, on occasion, be visible to the naked eye. On some rare occasions, a near-Earth asteroid may briefly become visible without technical aid; see 99942 Apophis.
10 Hygiea
Hygiea is the main member of the Hygiea family and contains almost all the mass (well over 90%) in this family. It is the largest of the class of dark C-type asteroids that are dominant in the outer asteroid belt—which lie beyond the Kirkwood gap at 2.82 AU. Hygiea appears to have a noticeably oblate spheroid shape, with an average diameter of 444 ± 35 km and a semimajor axis ratio of 1.11. This is much more than for the other objects in the "big four"—2 Pallas, 4 Vesta and the dwarf planet Ceres. Aside from being the smallest of the four, Hygiea, like Ceres, has a relatively low density, which is more comparable to the icy satellites of Jupiter or Saturn than to the terrestrial planets or the stony asteroids.