Pluto is in the asteroid belt.
The Kuiper belt ( [ ` kaipər ] or [ ` kœy̯pǝr ] ) , sometimes called the Edgeworth -- Kuiper belt , is a circumstellar disc in the Solar System beyond the ( known ) planets , extending from the orbit of Neptune ( at 30 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 . Pluto is the largest and most massive member of the Kuiper belt , and the largest and the second-most-massive known TNO , surpassed only by Eris in the scattered disc . Pluto . It was the first Kuiper belt object to be discovered .