Second object in asteroid belt to be discovered and third protoplanet recognised. Appears to be the largest irregularly shaped object in the solar system, larger than fellow protoplanet Vesta, but not as massive. Hubble identified color variations and features that could be linked to its thermal evolution. Orbit is unusually inclined, making it particularly inaccessible to spacecraft. Axis is extremely tilted so that much of body experiences half-year long days. Two satellite sightings have been reported, but later refuted. Has large crater from an impact that may have created the Pallas family of asteroids. The Dawn mission could flyby the asteroid if extended.