On January 1

The NASA space probe New Horizons flew by the trans-Neptunian object Arrokoth, making it the farthest object visited by a spacecraft.

A suicide bombing took place outside a Coptic Orthodox Church in Alexandria, Egypt, following a New Year service, killing 23 people.

A suicide bomber killed 105 spectators at a volleyball game in the Lakki Marwat District of Pakistan.

Adam Air Flight 574 crashed into the sea off Polewali, Indonesia, killing all 102 people on board, when the pilots inadvertently disconnected the autopilot.

Argentinian physicist Juan Maldacena published a landmark paper initiating the study of AdS/CFT correspondence, which links string theory and quantum gravity.

The World Trade Organization, the international organization designed to supervise and liberalize international trade, came into being, replacing the General Agreement on Tariffs and Trade.

The revolutionary leftist Zapatista Army of National Liberation initiated twelve days of armed conflict in the Mexican state of Chiapas.

Air India Flight 855 (aircraft pictured) crashed into the Arabian Sea seconds after take-off, killing all 213 people.

The People's Democratic Party of Afghanistan, which later helped the country become a republic, was founded.

Three men were killed and two wounded in a mass shooting at a public house in Sheffield, England.

The revised Thai criminal code came into force, strengthening the law on lèse-majesté in Thailand to include insult and treating it as a crime against national security.

British Railways came into existence when the "Big Four" railway companies were nationalised.

Second World War: The Luftwaffe launched Operation Bodenplatte in an attempt to cripple Allied air forces in the Low Countries.

World War II: In retaliation for the massacre of captured Americans by Waffen SS soldiers, U.S. Army personnel killed an estimated 80 Wehrmacht prisoners near Chenogne, Belgium.

Joseph Stalin's personal secretary, Boris Bazhanov, crossed the Iranian border and defected from the Soviet Union.

Ireland's first broadcaster, 2RN, began broadcasting.

Russia withdraws from its occupation of northwestern Iran, enabling a subsequent Ottoman invasion and massacres of Assyrians and Armenians.

The St. Petersburg–Tampa Airboat Line in the U.S. state of Florida became the first scheduled airline using a winged aircraft.

The immigration station on Ellis Island (pictured) in New York Harbor opened, and would process almost 12 million immigrants to the United States over the course of its existence.

Lachlan Macquarie (pictured) became Governor of New South Wales, eventually playing a major role in the social, economic and architectural development of the colony in Australia.