Phaiton

"Phaiton" was the name given by Galileo Galilei to what he believed to be a planet between the Sun and Mercury. (AUDIO: The Galileo Trap) In fact, it was an ancient stellar manipulator which had been forgotten about by the Time Lords until the Eleven located it using the Regeneration Codex.

The Eleven changed the manipulator into a Victorian workhouse staffed by artificial people and Orbs as part of a trap for the Eighth Doctor. He planned to kill the Doctor to power the manipulator and destroy the Sun, which would, in turn, destroy Mercury, Earth and Venus. However, he was stopped by the Doctor, Liv Chenka and Helen Sinclair and the manipulator destroyed. (AUDIO: The Satanic Mill)