Castor 36

Castor 36 was a planet far out beyond Alpha Geminorium.

History
The Sontarans promised to take genius Luke Rattigan and the students of Rattigan Academy to Castor 36, in exchange for his assistance in placing ATMOS in human motor vehicles. Luke's ideas for the planet's new name included Rattigan's World and Earth Point Two. However, the Sontaran leader, General Staal, later admitted that Castor 36 was a lie to trick Rattigan and his students. (DW: The Poison Sky)