The Kuiper Belt is a circumstellar disc in the outer Solar System, extending from the orbit of Neptune (at 30 astronomical units, AU) to approximately 50 AU from the Sun. It is similar to the Asteroid Belt but is far larger—20 times as wide and 20 to 200 times as massive. The Kuiper Belt is home to many small Solar System bodies composed largely of frozen volatiles such as methane, ammonia, and water.
