1986

By 1986, International Space Command had regular lunar flights and maintained a tracking station in Antarctica. (TV: The Tenth Planet; PROSE: Mondas Passing)

Several companions of the Doctor were born in 1986: Rose Tyler, being roughly 19 years old at the start of her travels with the Ninth Doctor (TV: The Unquiet Dead, Dalek, Army of Ghosts, PROSE: Rose Tyler, et al.) on 5 March 2005, (TV: Aliens of London) Martha Jones, (PROSE: Wooden Heart, The Story of Martha) and Clara Oswald. (TV: Death in Heaven)

While in a bubble prison, Iris Wildthyme imagined singing a duet with Elton John at Freddie Mercury's 40th birthday party in 1986. (AUDIO: Whatever Happened to Iris Wildthyme?)

Prior to December
The Doctor and Peri went to the London sewers as the Doctor detected a Time Wake in the Time Vortex, which linked London in January 1986 to London in 1720. (PROSE: Time Wake)

On 28 January, the space shuttle Challenger exploded, killing all seven of its crew. (PROSE: Return of the Living Dad, Father Time)

On 26 April, the nuclear power plant in Chernobyl in the Soviet Union went into meltdown. (COMIC: Black Destiny; AUDIO: Power Play) 40,000 people died of cancer as a result of the disaster. (PROSE: Iceberg)

In September, Edward Grainger was invited to a dinner with three of his former British Intelligence colleagues. (PROSE: Old Boys)

On 23 November, Clara Oswald was born. (TV: Death in Heaven)

December
In December, humans first detected the planet Mondas returning to the solar system. It apparently was in orbit between Mars and Venus. The manned atmospheric probe Zeus IV was destroyed by the planet's Cyberman inhabitants and they launched an attack on Earth, starting with the Snowcap base in Antarctica. They planned to use a Z-bomb located there to destroy Earth as one of the two worlds needed to be destroyed to save the other. When they failed, Mondas was destroyed instead. Present for these events was the First Doctor and while the Cybermen were defeated, the strain of the conflict led to his subsequent regeneration from his first incarnation into his second. (TV: The Tenth Planet)

Refusing to regenerate, the Twelfth Doctor's TARDIS took him to the South Pole where he encountered the First Doctor as he himself was hesitating to change. (TV: The Doctor Falls) This caused a timeline error which resulted in World War I combatant Archibald Hamish Lethbridge-Stewart being deposited at that time before the two Doctors, causing a glass avatar of the Testimony to pursue him. After saving Lethbridge-Stewart's life, the two Doctors parted ways with the First Doctor returning to meet his fate at the South Pole while the Twelfth Doctor faced his own regeneration. (TV: Twice Upon a Time)

Professor Allison Williams led the scientific team which investigated the Cyberman ship in Antarctica. (PROSE: The Power of the Daleks)

Twenty years after they helped the First Doctor prevent the return of Mondas in the then-future year of 1986 in their personal timelines, Ben Jackson and Polly Wright — who had gone their separate ways in life following a brief relationship after their return to Earth on 20 July 1966 — reunited on New Year's Eve in 1986, which was by then their present. Ben believed that numerous governments may have covered up the return of Mondas and the Cybermen invasion of the Snowcap. (PROSE: Mondas Passing)

Undated events
Toshiko Sato's family moved back to the UK from Japan this year. (TV: Greeks Bearing Gifts)

James Stevens' former father-in-law Lord Howarth died this year. His ex-wife Natasha allowed him to see his son William. (PROSE: Who Killed Kennedy)

Sherman Pegg entered his time travel model in his school science fair, where he met the Second Doctor. (AUDIO: The Way Forwards)

Benny Goodman died. (AUDIO: The Entropy Composition)