Kuiper Belt

The Kuiper Belt was a Sol System asteroid belt consisting of rocks and planetoids, located between Neptune and the Oort cloud. (AUDIO: The First Wave) It was very old, and was composed of the rocks that didn't form into planets or moons, as well as several dwarf planets. (PROSE: Observer Effect)

History
It was first discovered by Earth astronomers in 1992. (PROSE: Observer Effect)

It was situated around 53 AU from Sol. Around Steven Taylor's time, tens of thousands of mining stations were set up across the belt, so that rather than looking up at stars, one would see the working furnaces of the mines. One of these stations was Grace Alone. (AUDIO: The First Wave)

The Fourth Doctor and Sarah Jane Smith visited a spacecraft that was stationed in the Kuiper Belt. (PROSE: Observer Effect)

A Cyberman Cyber-Citadel was located on a Kuiper Belt dwarf planet, Planetoid X. (AUDIO: Last of the Cybermen)