In History, Today on December 21

The Great Conjunction of Jupiter and Saturn occurs, where the two planets appear closest together in the sky since 1623, an event sometimes referred to as the 'Christmas Star'.

The National Synchrotron Light Source II (NSLS-II) at the Brookhaven National Laboratory officially began operations, representing a major advancement in materials science and biology research facilities in the U.S.

A partial government shutdown began in the United States after Congress and President Donald Trump failed to agree on a budget, primarily due to disputes over funding for a border wall.

The United States Congress passed the Tax Cuts and Jobs Act, a major overhaul of the U.S. tax code, which included significant tax cuts for corporations and individuals.

The United Nations General Assembly adopted a resolution demanding an immediate ceasefire in Syria and the lifting of sieges, particularly in Aleppo, to allow humanitarian aid to reach civilians.

SpaceX successfully lands its Falcon 9 rocket's first stage on solid ground for the first time, marking a significant milestone in reusable rocket technology.

The world did not end, contrary to the popular interpretation of the Mayan calendar, which some believed predicted an apocalypse on this date.

The United States Census Bureau announced that the population of the United States officially hit 308,745,538 as of the 2010 Census, highlighting the demographic changes over the past decade.

The Schengen Agreement expanded to include nine new countries: the Czech Republic, Estonia, Hungary, Latvia, Lithuania, Malta, Poland, Slovakia, and Slovenia. This expansion allowed for the removal of border controls between these countries and the existing Schengen Agreement members, facilitating easier travel across much of Europe.

Ellen Johnson Sirleaf is officially confirmed as the winner of Liberia's presidential election, making her Africa's first elected female head of state.

The U.S. Department of Defense announced the creation of the Joint Unmanned Combat Air Systems (J-UCAS) program, aimed at developing unmanned aerial vehicles for combat purposes.

Eleven of the former Soviet republics, excluding the Baltic states and Georgia, met in Alma-Ata, Kazakhstan, and formally created the Commonwealth of Independent States (CIS), effectively marking the dissolution of the Soviet Union.

Pan Am Flight 103 was destroyed by a terrorist bomb over Lockerbie, Scotland, killing all 259 people on board and 11 on the ground, leading to international investigations and sanctions.

Lancaster House Agreement signed in London, granting independence to Rhodesia under the new name Zimbabwe, officially ending the 15-year civil war and marking a significant transition in southern Africa's colonial history.

Elvis Presley met President Richard Nixon at the White House, a famous meeting where Presley expressed his desire to help combat drug use.

Apollo 8, the first manned mission to orbit the Moon, was launched from the Kennedy Space Center, marking a significant achievement in the space race.

Charles de Gaulle was elected as the first President of the French Fifth Republic, establishing the framework for executive power in modern France and marking a key moment in French political history.

Adolf Hitler becomes Supreme Commander-in-Chief of the German Army.

The first full-length animated feature film, Disney's 'Snow White and the Seven Dwarfs,' premiered at the Carthay Circle Theatre in Los Angeles, California.

The first crossword puzzle was published in the New York World, created by journalist Arthur Wynne, marking the beginning of a popular pastime.

Pierre and Marie Curie discovered the radioactive element radium.

The world premiere of Henrik Ibsen's play 'A Doll's House' takes place at the Royal Theatre in Copenhagen, Denmark.

The Challenger expedition, a pioneering oceanographic expedition, set sail from Portsmouth, England, marking the beginning of modern oceanography.

The Rochdale Society of Equitable Pioneers opened their store, marking the beginning of the cooperative movement.

The Great Fire of New York concludes after devastating 17 city blocks and destroying hundreds of buildings.

The Baltimore and Ohio Railroad, one of the first common carrier railroads, was chartered by the Maryland legislature.

Nguyễn Huệ proclaims himself Emperor Quang Trung of Vietnam.

The Pilgrims on board the Mayflower land at Plymouth Rock, Massachusetts.

The Battle of Curalaba took place, marking a significant victory for the Mapuche people against Spanish colonial forces in Chile. This event initiated a period of Mapuche resistance known as the Destruction of the Seven Cities.

The Treaty of Bärwalde was signed between France and Sweden. This treaty was part of the Thirty Years' War, where France agreed to support Sweden financially in its fight against the Holy Roman Empire.

King Carloman II of West Francia dies, leading to the eventual unification of the Frankish kingdom under Charles the Fat.

Hincmar, Archbishop of Reims, dies. He was a significant figure in the Carolingian Renaissance, known for his theological writings and political influence.

The Roman Senate declared Vespasian the Roman Emperor, marking the end of the Year of the Four Emperors. This event was significant as it stabilized the Roman Empire after a period of chaos following the death of Emperor Nero and set the stage for the rise of the Flavian dynasty.