17 April 1967

NASA announced the discovery of Kepler-186f, the first exoplanet with a radius similar to Earth's discovered in the habitable zone of another star.

An ammonium nitrate explosion occurred at a fertilizer company facility in West, Texas, U.S., killing 15 people and injuring 160 others.

A Palestinian suicide bomber detonated explosives in a restaurant in Tel Aviv, Israel, killing 11 people and injuring 70 others.

The Netherlands and the Isles of Scilly declared peace, having hypothetically been at war for 335 years without a single shot being fired and no casualties incurred.

Metropolitan Police officer Yvonne Fletcher was shot and killed while on duty during a protest outside the Libyan embassy in London, resulting in an 11-day police siege of the building and a breakdown of Libya–United Kingdom relations.

The Khmer Rouge captured Phnom Penh, the capital of the Khmer Republic, ending the Cambodian Civil War and establishing the socialist state of Democratic Kampuchea.

George Lucas began writing a 13-page film treatment that later formed the basis of Star Wars.

Czechoslovak Communist Party chairman Alexander Dubček was deposed.

Sirhan Sirhan was convicted of the assassination of U.S. senator Robert F. Kennedy.

The Peak District was designated the first national park in the United Kingdom.

World War II: Captured French general Henri Giraud escaped from German captivity in the Königstein Castle.

Minas Geraes (pictured), the first of three Brazilian dreadnought battleships, was laid down, sparking a vastly expensive South American naval arms race with Argentina and Chile.

Napoleonic Wars: After a three-day chase, the French ship D'Hautpoul was captured off Puerto Rico by a British squadron under Alexander Cochrane.

French Revolutionary Wars: British forces commanded by Lieutenant-General Ralph Abercromby invaded the Spanish colonial port of San Juan, Puerto Rico.

The Mechanical Turk (pictured), a fraudulent chess-playing "machine" by Wolfgang von Kempelen that was secretly controlled by a hidden human, began a tour of Europe.

Lithuanian Crusade: After a month-long siege, the Teutonic Order captured and destroyed Kaunas Castle, which was defended by troops of the Grand Duchy of Lithuania.

Canute IV became King of Denmark upon the death of his brother Harald III.

The funeral of Prince Philip, Duke of Edinburgh, takes place at St George's Chapel, Windsor Castle.

NASA's Kepler space telescope confirms the discovery of the first Earth-size planet in the habitable zone of another star.

An explosion at a fertilizer plant in the city of West, Texas, kills 15 people and injures 160 others.

The ceremonial funeral of former British prime minister Margaret Thatcher takes place at St Paul's Cathedral.

A Palestinian suicide bomber detonates an explosive device in a Tel Aviv restaurant, killing 11 people and injuring 70.

Anneli Jäätteenmäki takes office as the first female prime minister of Finland.

Space Shuttle Columbia is launched on STS-90, the final Spacelab mission.