The Kuiper belt (pronounced /'ka?p?/) is an area of the solar system extending from the orbit of Neptune (at 30 AU) to 50 AU from the Sun.
The objects within the Kuiper Belt together with the members of the scattered disk extending beyond, are collectively referred to as trans-Neptunian.
The interaction with Neptune (2:1 orbital resonance) is thought to be responsible for the apparent edge at 48 AU (a sudden drop in number of objects) but the current models have yet to explain this peculiar distribution in detail.