Ceres is the asteroid belt's biggest object — and a quarter of its mass

Dwarf planet Ceres is the largest object in the asteroid belt between Mars and Jupiter and the only dwarf planet in the inner solar system, NASA notes. It is also a useful exercise in scale: Ceres accounts for 25 percent of the asteroid belt's total mass, which tells you how little the rest of that crowded-looking region adds up to. The comparison cuts the other way too — Pluto is still 14 times more massive than Ceres. Largest in the belt does not mean large.