Castor 36

Castor 36, named Earth.2 and Rattigan's World by Luke Rattigan, was a planet far out beyond Alpha Geminorum.

The Sontarans promised to take human genius Luke Rattigan and the students of Rattigan Academy to Castor 36, in exchange for his assistance in placing ATMOS in human motor vehicles. However, the Sontaran leader, General Staal, later admitted that Castor 36 was a lie to trick Rattigan and his students. (TV: The Poison Sky)