21 January

On 21 January 1941, the original Captain Jack Harkness died in combat. (TV: Everything Changes, Captain Jack Harkness)

In London, the ex-Time Agent masquerading as Jack Harkness failed to report for duty. According to a detailed search of UK records performed by Gwen Cooper's police colleague Yvonne, he was never heard from again. (TV: Everything Changes) The evening of 20 January 1941 was therefore the time when "Captain Jack" began travelling in the TARDIS with the Ninth Doctor and Rose Tyler. (TV: The Doctor Dances)

In 1979, Dan Hodges was born. (TV: Combat)

In 1981, the Fourth Doctor, Romana II and K9 Mark II visited Norway. (COMIC: A Midsummer's Nightmare)

In 2004, NASA's Mars rover Spirit temporarily lost communication with Earth for two days due to problems with the computer's memory or, as one source suggested, Ice Warrior interference. (PROSE: Time Traveller's Diary)