Asked by: Adam King, Huddersfield
Surprisingly, the total mass of material in the asteroid belt is only about 4 per cent of the mass of the Moon. About half of this mass is contained in the four largest asteroids: Ceres, Vesta, Pallas and Hygiea. If all this material were concentrated into a single object with the same density as Ceres, it would be a dwarf planet about 700km in radius (Pluto, another dwarf planet, has a radius of 1,188km).
Such a small object would have little impact on the Solar System as a whole.