Gallifrey

Gallifrey is a fictional planet in the long-running British science fiction television series Doctor Who and is the home world of the Doctor and the Time Lords. It is located in a binary star system (Gridlock) within the constellation of Kasterborous (Pyramids of Mars, Attack of the Cybermen and Voyage of the Damned), at "galactic coordinates ten-zero-eleven-zero-zero by zero-two from galactic zero centre" (Pyramids of Mars (1975), Full Circle (1980) and partially in "The Family of Blood" (2007)), which is some 250 million light years away from Earth (as stated in the 1996 Doctor Who television movie). This would put it far outside our Milky Way galaxy, which is about a hundred thousand light years in diameter, and indeed outside the Local Group and even the Virgo Supercluster; however, at this distance it would still be within the Pisces-Cetus Supercluster Complex.

During the first decade of the television series, the name of the Doctor's home planet was not revealed, although it was actually shown for the first time in The War Games (1969) during the Doctor's trial. It was finally identified by name for the first time in The Time Warrior (1973). It is never definitively stated when the appearances of Gallifrey in the television series take place. As the planet is often reached by means of time travel, its relative present could conceivably exist anywhere in the Earth's past or future before the year 100 trillion, which the Time Lords never reached.

Gallifrey's position in the revived series (2005 onwards) was filled in slowly over the first three years of the series' run. In Series 1, it had been implied that it was destroyed along with the Dalek Empire, by the Doctor during the Time War. The planet was not referred to by name until the 2006 Christmas Special, was depicted in a flashback in "The Sound of Drums", and played an important role in the plot of "The End of Time".