The Kuiper belt, sometimes called the Edgeworth–Kuiper belt, is a circumstellar disc in the Sol system beyond the planets, extending from the orbit of Neptune (at 30 AU) to approximately 50 AU from Sol. It is similar to the asteroid belt, but it is far larger—20 times as wide and 20 to 200 times as massive. Like the asteroid belt, it consists mainly of small bodies, or remnants from the Sol system's formation.
Although many asteroids are composed primarily of rock and metal, most Kuiper belt objects are composed largely of frozen volatiles (termed "ices"), such as methane, ammonia and water. The Kuiper belt is home to three officially recognized dwarf planets: Pluto, Haumea, and Makemake. Some of the Sol system's moons, such as Neptune's Triton, are also thought to have originated in the region.
Prior to the protomolecule's discovery, Phoebe was thought to have originated from the Kuiper belt as well.