Mettula Orionsis
Mettula Orionis was a star system that contained the planet Traken, the capitol of the Traken Union. It is possible that either Metulla Orionsis was one of the systems of the Union or if it was the entire Union. At least three planets were seen to make up the system (one being Traken), though it is possible the other two were Traken's moons. (TV: The Keeper of Traken) Nyssa once described Mettula Orionis as a constellation rather than a "star system". (PROSE: Divided Loyalties)
In 1981, a temporary wave of entropy swept across part of the universe, destroying Metulla Orionsis in the process. (TV: Logopolis)
Contemplating the Butterfly Effect, the Doctor thought of how a butterfly flapping its wings in Mettula Orionis could have great great concequences elsewhere. (PROSE: Transit)
