Skonnos

Skonnos is a planet first shown in The Horns of Nimon. It was a brown, dirty planet with a grey sky, though this may be because of the Skonnans or Nimons. Before the events of The Horns of Nimon, the planet was ruled by the first Skonnan Empire, but it collapsed due to infighting. Eventually, they were discovered by the Nimon, who bribed them with advanced technology. Though the Nimons planned to use the energy of Skonnos themselves, they were stopped by the Fourth Doctor, Romana and K-9 (with some help by the Anethan).