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Introduction

Centaur (astronomy), small comet-like body that orbits the Sun in the outer solar system between the giant planets Jupiter and Neptune. Centaur objects such as Chiron typically have highly elliptical orbits that may cross the orbits of one or more of the outer planets (Jupiter, Saturn, Uranus, and Neptune).

Centaurs are made of ice, dust, and rock, and range in shape from nearly spherical to elongated. They show a range of colors from dark gray to reddish. Astronomers have detected water ice and carbon compounds on their porous surfaces. A few centaurs, including Chiron, sometimes release gas and dust like comets. Other centaurs, however, show no such cometary activity.