April 20
1865: Italian astronomer Angelo Secchi demonstrated for the first time his Secchi disk, which measures water turbidity, aboard L’Immaculata Concezion, the yacht belonging to Pope Pius IX.
1926: Western Electric and Warner Bros. announced Vitaphone, a process to add sound to film.
1939: Billie Holiday (1915-1959) recorded the first Civil Rights song, “Strange Fruit.”
1951: Romanian surgeon Dan Gavriliu (1915-2012) performed the first successful surgical replacement of a human organ. He replaced an esophagus using sections of stomach to bypass damaged or deformed tissue.
1972: Apollo 16, commanded by John Young, landed on the moon.
2008: Danica Patrick won the Indy Japan 300 to become the first female driver in history to win an Indy car race.
April 21
753 BC: Romulus and Remus founded Rome.
1782: The city that would become Bangkok, Thailand, was founded.
1926: Britain’s Queen Elizabeth II was born in London.
1934: The “Surgeon’s Photograph,” the most famous photo allegedly showing the Loch Ness Monster, was published in the Daily Mail. (It is revealed to be a hoax in 1999.)
1988: The Shroud of Turin—the purported burial shroud of Jesus Christ—underwent carbon dating and was shown to have been made in about 1300.
April 22
1876: The first ever National League baseball game was played in Philadelphia.
1970: The first Earth Day was celebrated.
1977: Optical fiber was first used to carry live telephone traffic.
1994: Richard Milhous Nixon, 37th U.S. president, died at age 81 in New York.
April 23
1635: The first public school in the United States, Boston Latin School, was founded in Boston, Mass.
1914: The first baseball game was played at Wrigley Field, then known a Weeghman Park, in Chicago.
1985: Coca-Cola changed its formula and released New Coke. The response was overwhelmingly negative and the original formula was back on the market in less than three months as “Classic Coke.”
2005: The First YouTube video was uploaded, titled “Me at the zoo.”
April 24
1184 B.C.: The city of Troy fell to Greek invaders.
1704: The first newspaper in the United States, the News-Letter, began publishing in Boston.
1800: The U.S. Library of Congress was established when President John Adams signed legislation to appropriate $5,000 to purchase “such books as may be necessary for the use of Congress.”
1967: Cosmonaut Vladimir Komarov became the first person to die during a space mission after the parachute of his capsule failed to deploy following re-entry.
April 25
1859: British and French engineers broke ground for the Suez Canal to connect the Red Sea to the Mediterranean Sea.
1901: New York became the first U.S. state to require automobile license plates.
1945: Fifty nations gathered in San Francisco, Calif., to begin the United Nations Conference on International Organizations.
1953: Francis Crick and James D. Watson published “Molecular Structure of Nucleic Acids: A Structure for Deoxyribose Nucleic Acid” describing the double helix structure of DNA.
1974: Workers for the Dowling Construction Co. of Indianapolis left a five-ton steel wrecking ball hanging from a crane 200 feet above the ground. When they returned the next morning, the ball was gone. Police had no explanation and the ball was never found.
1983: Pioneer 10 traveled beyond Pluto’s orbit to become the first manmade object to leave the Solar System.
April 26
1956: The world’s first successful container ship, SS Ideal X, left Port Newark N.J. for Houston, Texas.
1986: A nuclear reactor accident at the Chernobyl Nuclear Power Plant in the Soviet Union (now Ukraine), created the world’s worst nuclear disaster.