New ground-based observations with ESO’s SPHERE instrument on the Very Large Telescope have revealed that the surface of the asteroid Hygiea lacks a large impact crater. Because it was formed from one of the largest impacts in the history of the asteroid belt, astronomers were expecting to find at least one large, deep impact basin, similar to the one on Vesta (bottom right in the central panel).
The new study also found that Hygiea is spherical. That would mean that it rather than Ceres is the smallest dwarf planet in the Solar System. Hygiea’s diameter is just over 430 km, a bit less than half that of Ceres (950 km).
Image Credit: ESO