An asteroid is a rocky body which is gravitationally bound to and orbits the Sun. The majority of asteroids lie in a region called the asteroid belt which is located between the orbits of Mars and Jupiter. Some of the largest asteroids are listed in the table below.

Asteroids whose orbits have been determined carefully enough so that their position on the sky as a function of time can be predicted are assigned permanent numbers and names by the Minor Planet Center. At present, there are more than 8,700 numbered asteroids (Minor Planet Center, Schmadel 1997). Astroid names are chosen by the discoverer, and some noteworthy names assigned to asteroids are 3834 Zappafrank, 2906 Caltech, 2404 Antarctica, 5102 Benfranklin, 7850 Buenos Aires, 10221 Kubrick, etc.

Asteroids are placed in families having similar orbits, with the most common families being the Amor, Apollo, and Aten groups, each named after a prominent asteroid in a given group. The approximate number of known members of each group is listed in the following table (Minor Planet Center). Earth-crossing asteroids are called Apollo asteroids. A table of large Apollo asteroids is contained in Sky & Telescope (March 1990).

Class	Perihelion	a (AU)	Crossing	# km
Amor	1.0-1.3		Mars	231
Apollo			Earth	240
Aten			Venus	30

Airburst, Amor Asteroid, Apollo Asteroid, Asteroid Belt, Aten Asteroid, Comet, Kuiper Belt, Meteorite, Tunguska Event