The region of the Solar System between the orbits of Mars and Jupiter in which most asteroids are found; also known as the main belt. It extends from 2.1 to 3.3 AU from the Sun, corresponding to orbital periods of 3.0–6.0 years. Asteroids are not uniformly distributed throughout the belt. There are sparsely populated zones, known as Kirkwood gaps, as well as concentrations of asteroids with similar orbital elements, forming groups and Hirayama families. The proportion of various asteroid classes changes markedly through the belt (see Asteroid).
Subjects: Astronomy and Astrophysics.