Avalon (planet)
From Tardis Wiki, the free Doctor Who reference
Avalon was planet with six moons. The planet was discovered near the end of the Earth Empire. Once home to an advanced race, it was colonised by humans, setting up a nation named Elbyon. The Doctor visited Avalon circa 3025. (MA: The Sorcerer's Apprentice)
Using nanomachines and a nova trigger, they attempted to force the Empire's planets to stay together towards the end of the Empire, though they were unsuccessful. (MA: The Dark Path)
