This Day In History : April 21

1908 United States

Frederick Cook Claims First North Pole Expedition

On April 21, 1908, American polar explorer Frederick Cook claimed to have reached the North Pole. This assertion has been widely disputed and remains a topic of controversy. Cook's claim predates Robert Peary's well-known 1909 expedition.

Also on This Day in History April 21

Discover what happened on April 21 with HISTORY's summaries of major events, anniversaries,
famous births and notable deaths.

Births on This Day, April 21
  • 1951 Michael Hartley Freedman

    American mathematician who was awarded the Fields Medal in 1986 for his proof of the conjecture in four dimensions (1982).

  • 1830 James Starley

    British inventor and manufacturer, known as the father of the bicycle industry.

  • 1843 Walther Flemming

    German anatomist who was the first to observe and describe systematically the behaviour of chromosomes in the cell nucleus during normal cell division (mitosis, a term he coined in 1882).

  • 1889 Paul Karrer

    Swiss chemist who investigated the constitution of carotenoids, flavins, and vitamins A and B2, for which he shared the 1937 Nobel Prize for Chemistry (with Sir Norman Haworth of Great Britain).

  • 1882 Percy W. Bridgman

    American experimental physicist noted for his studies of materials at high temperatures and pressures.

Deaths on This Day, April 21
  • 1965 Edward Victor Appleton

    English physicist who was awarded the 1947 Nobel Prize for Physics for his discovery of the Appleton layer of the ionosphere.

  • 1835 Samuel Slater

    English-American mechanical engineer who founded the American cotton-textile industry.

  • 1825 Johann Friedrich Pfaff

    German mathematician who proposed the first general method of integrating partial differential equations of the first order.

  • 1926 Henry Christopher Mance

    British scientist and engineer whose invention of a heliograph provided a portable signaling device that used a tripod with a mirror to reflect sunlight (British patent Feb 1876).

  • 1965 Edward Appleton

    English physicist who was awarded the 1947 Nobel Prize for Physics for his discovery of the Appleton layer of the ionosphere.

1972

Apollo 16

In 1972, Apollo 16 astronauts landed for a fifth manned mission to the moon's surface. The Lunar Module Orion with John W. Young and Charles M. Duke set down in the central lunar highlands to explore a different terrain than any previous astronauts had seen. The crew travelled almost 27-km using their lunar rover.
1962

Seattle World's Fair (Century 21 Exposition) Opens

On April 21, 1962, the Seattle World's Fair, also known as the Century 21 Exposition, officially opened. The event showcased futuristic innovations and architectural marvels, including the iconic Space Needle. It attracted millions of visitors and left a lasting legacy on the city.
1997

1997 Ashes of Timothy Leary and Gene Roddenberry Launched into Space

On April 21, 1997, the ashes of psychologist and author Timothy Leary and "Star Trek" creator Gene Roddenberry were launched into space orbit. This unique tribute honored their contributions to science, exploration, and imagination. The space burial marked a new frontier in memorial services.
1994

1994 First Discoveries of Extrasolar Planets Announced

On April 21, 1994, astronomer Alexander Wolszczan announced the first discoveries of extrasolar planets. These planets, located outside our solar system, were found orbiting a pulsar. This groundbreaking discovery significantly expanded our understanding of the universe.
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