January 25 – Yoweri Museveni's National Resistance Army Rebel group takes over Uganda after leading a five-year guerrilla war in which up to half a million people are believed to have been killed. They will later use January 26 as the official date to avoid a coincidence of dates with Dictator Idi Amin's 1971 coup.
February 9 – Halley's Comet reaches its perihelion, the closest point to the Sun, during its second visit to the solar system in the 20th century (the first was in 1910).
A three-day riot begins in Cairo, Egypt when around 25,000 conscripts of the Central Security Forces (CSF), staged protests in and around the city. Three luxury hotels, several nightclubs, restaurants and cars were looted and burned in the tourist districts near the Pyramids over several days.[6] The riot became known as the Egyptian Conscripts Riot. At least 25 people died during the first day in Cairo, and an estimated 8,000 people, mostly conscripts in regions outside the city, were killed in total.
March 1 – Olof Palme's deputy Ingvar Carlsson becomes acting Prime Minister of Sweden. He is elected Prime Minister by the Swedish Riksdag on March 15.
March 9 – United States Navy divers find the largely intact but heavily damaged crew compartment of the Space Shuttle Challenger; the bodies of all seven astronauts are still inside.
Lebanon hostage crisis: British journalist John McCarthy is kidnapped in Beirut (he is released in August 1991) and three others are killed in retaliation for the bombing of Libya.
The Hindawi affair begins when an Irishwoman is found carrying explosives onto an El Al flight from London to Tel Aviv.
An alleged state of war lasting 335 years between the Netherlands and the Isles of Scilly declared peace bringing an end to any hypothetical war that may have been legally considered to exist.
April 18 – Titan 34D-9 explodes just after launch while carrying the final KH-9 satellite.[10]
April 26 – Chernobyl disaster: A mishandled safety test at the Chernobyl Nuclear Power Plant in Pripyat, Ukrainian SSR, Soviet Union "killed at least 4,056 people and damaged almost $7 billion of property".[11] Radioactive fallout from the accident is concentrated near Belarus, Ukraine and Russia and at least 350,000 people are forcibly resettled away from these areas. After the accident, "traces of radioactive deposits unique to Chernobyl were in nearly every country in the northern hemisphere".[11]
A low-pressure system moving from South Australia and redeveloping off the New South Wales coast dumps a record 328 millimetres (12.9in) of rain in a day on Sydney.
August 19 – Two weeks after it was stolen, the Picasso painting Weeping Woman is found in a locker at the Spencer Street Station in Melbourne, Australia.
The cargo ship Khian Sea departs from the docks of Philadelphia, carrying 14,000 tons of toxic waste. It wanders the seas for the next 16 months trying to find a place to dump its cargo. The waste is later dumped in Haiti.
September
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September 13 – The 6.0 MwKalamata earthquake shook southern Greece with a maximum Mercalli intensity of X (Extreme). The shock left at least 20 dead, 300 injured, and caused $5million in damage.
October 22 – In New York City, WNBC Radio's traffic helicopter crashes into the Hudson River, killing traffic reporter Jane Dornacker. The last words heard on-the-air are Dornacker's screams of terror, "Hit the water! Hit the water! Hit the water!"
Queensland, Australia: Joh Bjelke-Petersen wins his final election as Premier of Queensland with 38.6% of the vote. He resigns on December 1, 1987, following revelations of his involvement with corruption released in the Fitzgerald Inquiry.
Iran–Contra affair: The Lebanese magazine Ash-Shiraa reports that the United States has been selling weapons to Iran in secret, in order to secure the release of 7 American hostages held by pro-Iranian groups in Lebanon.
The Northern Mariana Islands enter in a political union with the United States. The island's government adopted its own constitution in 1977, and the constitutional government took office in January 1978. The covenant was fully implemented November 3, 1986, pursuant to Presidential Proclamation no. 5564, which conferred United States citizenship on legally qualified island residents.
December 4 – The MV Amazon Venture oil tanker begins leaking oil while at the port of Savannah in the United States, resulting in an oil spill of approximately 500,000 US gallons (1,900,000L).[26]
Zalaquett, Cherie (2011). "La frentista "Fabiola": un relato en reversa del atentado a Pinochet" ["Fabiola": a reverse story on Pinochet attack]. Revista Izquierdas (in Spanish). 9: 1–30.