Historical timeline for December 21

Fourteen people are killed and 25 others injured during a mass shooting at Charles University in Prague, Czech Republic.

A Vega C rocket carrying two Pléiades Neo satellites fails after liftoff.

A great conjunction of Jupiter and Saturn occurs, with the two planets separated in the sky by 0.1 degrees. This is the closest conjunction between the two planets since 1623.

2012 phenomenon: Festivities are held in parts of Mesoamerica to commemorate the conclusion of b'ak'tun 13, a roughly 5,126-year-long cycle in the Mesoamerican Long Count Calendar whose passing many New Age spiritualists had earlier held to portend a variety of cataclysmic or transformative events.

Iraq War: A suicide bomber kills 22 at the forward operating base next to the main U.S. military airfield at Mosul, Iraq, the single deadliest suicide attack on American soldiers in Iraq.

Cubana de Aviación Flight 1216 overshoots the runway at La Aurora International Airport, killing 18.

The Spanish Civil Guard intercepts a van loaded with 950 kg of explosives that ETA intended to use to blow up Torre Picasso in Madrid, Spain.

The city of Bethlehem passes from Israeli to Palestinian control.

A Dutch DC-10, flight Martinair MP 495, crashes at Faro Airport, Portugal, killing 56.

Dissolution of the Soviet Union: The leaders of 11 now effectively autonomous Soviet republics sign the Alma-Ata Protocol establishing the Commonwealth of Independent States in place of the collapsing Soviet Union.

A bomb explodes on board Pan Am Flight 103 over Lockerbie, Dumfries and Galloway, Scotland, killing 270. This is to date the deadliest air disaster to occur on British soil.

Lancaster House Agreement: An independence agreement for Rhodesia is signed in London by Lord Carrington, Sir Ian Gilmour, Robert Mugabe, Joshua Nkomo, Bishop Abel Muzorewa and S.C. Mundawarara.

The Geneva Conference on the Arab–Israeli conflict opens.

Apollo program: Apollo 8 is launched from the Kennedy Space Center, placing its crew on a lunar trajectory for the first visit to another celestial body by humans.

Louis Washkansky, the first man to undergo a human-to-human heart transplant, dies in Cape Town, South Africa, having lived for 18 days after the transplant.

International Convention on the Elimination of All Forms of Racial Discrimination is adopted.

"Bloody Christmas" begins in Cyprus, ultimately resulting in the displacement of 25,000–30,000 Turkish Cypriots and destruction of more than 100 villages.

An 8.1 Mw earthquake and subsequent tsunami in Nankaidō, Japan, kills over 1,300 people and destroys over 38,000 homes.

World War II: A Thai-Japanese Pact of Alliance is signed.

Lieutenant Kijé, one of Sergei Prokofiev's best-known works, premiered.