In History, Today on October 21

NASA's Lucy spacecraft sends first signal back to Earth as it continues its mission to study the Trojan asteroids orbiting Jupiter.

Protests erupt in Chile over economic inequality and the cost of living, leading to widespread demonstrations and a state of emergency being declared.

Back to the Future Day was celebrated worldwide, marking the date that Marty McFly and Doc Brown traveled to in the movie 'Back to the Future Part II'.

The Libyan National Transitional Council declares the liberation of Libya, marking the end of the Libyan Civil War following the death of Muammar Gaddafi.

India launched its first lunar probe, Chandrayaan-1, marking a significant milestone in its space exploration efforts. The mission aimed to map the Moon's surface and search for water.

Panama approved the Panama Canal expansion project through a national referendum, allowing for increased shipping and larger vessels.

The final flight of the supersonic passenger airliner Concorde takes place from New York City to London Heathrow Airport, marking the end of an era in aviation history.

Chechen rebels seized a crowded Moscow theater, taking 850 hostages. The standoff lasted for several days, resulting in a siege by Russian security forces.

The United States and its allies began a major military offensive in Afghanistan, targeting Taliban and al-Qaeda forces as part of Operation Enduring Freedom.

The meter is defined as the distance light travels in a vacuum in 1/299,792,458 of a second, by the 17th General Conference on Weights and Measures.

A large Vietnam War protest occurs in Washington, D.C., as thousands of demonstrators march against the war.

The Aberfan disaster occurs as a colliery spoil tip collapses in the Welsh village of Aberfan, killing 144 people, including 116 children.

The Solomon R. Guggenheim Museum, designed by Frank Lloyd Wright, opened to the public in New York City.

World War II: The first kamikaze attack occurs as a Japanese plane carrying a 200-kilogram bomb attacks HMAS Australia off Leyte Island.

Florence Nightingale, the founder of modern nursing, was presented with the Order of Merit by King Edward VII.

Thomas Edison invents a workable electric light at his laboratory in Menlo Park, New Jersey.

Florence Nightingale and a staff of 38 nurses are sent to the Crimean War.

Alfred Nobel, the Swedish chemist, engineer, and inventor, was born. He is best known for inventing dynamite and establishing the Nobel Prizes.

The Battle of Trafalgar takes place, a naval engagement fought by the British Royal Navy against the combined fleets of France and Spain during the Napoleonic Wars, resulting in a decisive British victory.

The USS Constitution, also known as 'Old Ironsides', was launched in Boston Harbor. It became famous for its role in the War of 1812 against Great Britain.

The city of Hartford, Connecticut, was founded by Reverend Thomas Hooker to provide a place for a congregation that separated from a church led by Reverend John Davenport in New Haven.

Ferdinand Magellan discovers a strait now known as the Strait of Magellan, the passage immediately south of mainland South America connecting the Pacific and Atlantic Oceans.

Scottish resistance leader Andrew Moray dies of wounds sustained during the Battle of Stirling Bridge in September 1297, a crucial victory for the Scots in the First War of Scottish Independence.

The People's Crusade, part of the First Crusade, is decisively defeated by the Seljuk forces at the Battle of Civetot.

The Battle of Khaybar took place, where Muslim forces led by the Prophet Muhammad captured the Jewish oasis of Khaybar in the Arabian Peninsula.