Gemini
From Tardis Wiki, the free Doctor Who reference
Gemini was a constellation visible from Earth. It included the stars Castor and Pollux. Once Ian Chesterton showed it to Vicki Pallister. (PROSE: Byzantium!)
In 1746, in Inverness, the Second Doctor mentioned it while pretending to use astrologic criteria as a physician. (TV: The Highlanders)