Orion

Orion was the name of a constellation which was light years from Earth in the Mutter's Spiral galaxy. To observers on Earth, it was often likened to a human figure wearing a belt. (AUDIO: Autumn)

Astronomical data
Orion was in Mutter's Spiral. Though constellations typically contained stars hundreds of light-years apart, Orion was typically used to discuss a specific group of star systems. One such member was the double star system known as Bellatrix.

From southern England, it was possible to use Orion as a way to locate Traken. Nyssa told Andrew Harper that Traken was about halfway between Orion's belt and his left shoulder. (AUDIO: Autumn)

History
The Osiran race placed great importance on the constellation. (PROSE: Sands of Time)

While showing the constellation in Earth sky, Ian Chesterton told Vicki Pallister about the mythological figure from the Greek mythology after which the constellation was named. (PROSE: Byzantium!)

In the 26th century, Orion was settled by androids fleeing from persecution in the Earth Empire. They set up an independent society that demanded any humans in their territory must accept android rule or get out. The Earth Empire could not abide the restriction, and waged the Orion War in retaliation. (AUDIO: Sword of Orion, Cyberman'')

Parallel world
In a parallel world, the stars in the Orion constellation burnt out as a result of "the Darkness", (TV: Turn Left) also known as the reality bomb, which was detonated on the Crucible in the Doctor's world. (TV: Journey's End) This event was observed by Wilfred Mott through his telescope. (TV: Turn Left)