Tremulus Three

Tremulus Three was the star system containing the planet Telos, (PROSE: Attack of the Cybermen) as well as a smaller planetoid Professor Vansom called Telos Minor. (AUDIO: Secrets of Telos) It was near Tasker's Crown, (PROSE: Attack of the Cybermen) and was a neighbour to Krelos's star system, which contained several other planets with the "-os" suffix. (AUDIO: The Fate of Krelos / Return to Telos) The Fifth Doctor called this the Telos system. (AUDIO: Secrets of Telos)

Tremulus Three may also have contained the human colony Red Rocket Rising, as before Acting President Eileen Klint's message was cut off, she mentioned a world on the edge of their solar system whose name began with "Tel-." (AUDIO: Blood of the Daleks)