An asteroid belt is a torus-shaped region in the Solar System located between the orbits of the planets Mars and Jupiter. It contains a large number of solid, irregularly shaped bodies called asteroids or minor planets, which range widely in size from tiny rocks to dwarf planets like Ceres, the largest object in the belt

. The asteroid belt is the smallest and innermost circumstellar disc in the Solar System, spanning roughly 2 to 4 astronomical units (AU) from the Sun, which is about 140 million miles across. The asteroids are spaced on average about one million kilometers apart, making the region mostly empty space despite the large number of objects

. This belt formed from the primordial solar nebula as planetesimals but never coalesced into a planet due to gravitational disturbances from Jupiter, which caused collisions that shattered these bodies instead of allowing them to grow. As a result, the belt contains remnants from the early Solar System, essentially leftover building blocks that never formed into a planet

. The asteroid belt's total mass is estimated to be about 3% that of the Moon, with the four largest asteroids-Ceres, Vesta, Pallas, and Hygiea-holding about 60% of the belt's mass. The asteroids are classified mainly into three types based on their composition: carbonaceous (C-type), silicate (S-type), and metal-rich (M-type)

. Despite popular depictions in media, the asteroid belt is not densely packed; spacecraft have safely passed through it without incident due to the vast distances between asteroids

. In summary, the asteroid belt is a vast, sparsely populated region of rocky remnants orbiting the Sun between Mars and Jupiter, representing material left over from the Solar System's formation that never formed into a planet because of Jupiter's gravitational influence