Vulcan (Invasion of the Daleks)

Vulcan was a planet which supported a human colony.

Overview
Vulcan was roughly twelve parsecs away from any other colony. The atmosphere was breathable by humans. It had very little radiation and the average temperature was 30 degrees Celsius (86 degrees F). It was a young, volcanic world, with nutrient-rich soil, but with no native life. It had pools of fuming mercury. Vulcan's day was several hours shorter than Earth's. (TV: The Power of the Daleks)

History
Vulcan was colonised after humans discovered the mineral riches of the planet, a number of years before the Dalek invasion of Earth in the mid-22nd century. It was Earth's third ever colony. The planet was owned and the mining operations were funded by the Interplanetary Mining Corporation. They sought to keep things "economical", providing the colony with the bare necessities of technology and equipment. This built up resentment with a band of rebels who began secretly plotting against Governor Hensell, whom they viewed as an IMC mouthpiece. (PROSE: The Power of the Daleks)

The colony was almost taken over by Daleks, who had been found in a crashed spacecraft underground and then reactivated by a scientist called Lesterson. This overlapped with the rebellion against Hensell led by Bragen. The rebellion failed after the Daleks began an indiscriminate slaughter of the colonists but the Second Doctor overloaded their temporary static circuit from the colony's electricity supply. This left the colony without power for months. Quinn became Governor in the aftermath. (TV: The Power of the Daleks)

The Daleks that survived this encounter with the Doctor were classified as insane and were sent to the "intensive care" section of the Dalek Asylum. These Daleks were later destroyed when the Dalek Parliament blew up the planet. (TV: Asylum of the Daleks)

The Seventh Doctor and Elizabeth Klein visited the mercury swamps of Vulcan prior to their arrival on the Vrill colony. (AUDIO: Survival of the Fittest)

As Terri Willis told Ben Jackson, Vulcan was "practically a legend" by 2146. (PROSE: The Murder Game)

Behind the scenes

 * Scientists of the 19th and 20th centuries hypothesised the existence of a planet between the orbit of Mercury and Sol, and sometimes referred to that planet as Vulcan. This has since been discredited. The Taking of Planet 5 makes reference to this.
 * The Star Trek character Spock came from the fictional planet . Star Trek only just beat Doctor Who in introducing the concept of an alien world called Vulcan by a few weeks, as it debuted not quite two months before The Power of the Daleks aired. Both shows seem to have selected the name independently.