1983 the metre is defined as the distance light travels in a vacu 10 21
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1983 43 years ago Historical Events October 21

The metre is defined as the distance light travels in a vacuum in 1/299,792,458 of a second.

On October 21, in the year 1983, The metre is defined as the distance light travels in a vacuum in 1/299,792,458 of a second. This event is recorded as a Historical Events event in the history of October 21, one of 453 recorded events on this date across all of history.

The metre is the base unit of length in the International System of Units (SI). Since 2019, the metre has been defined as the length of the path travelled by light in vacuum during a time interval of ⁠1/299792458⁠ of a second, where the second is defined by a hyperfine transition frequency of caesium.

Key Facts

  • This event took place on October 21, 1983 (AD era).
  • It is categorised as a Historical Events event in recorded history.
  • Referenced in 1 Wikipedia article.
  • Wikipedia source last updated on 4 October 2026.

On This Date in History 453

Type Year Date Event
Notable Deaths 2025 Oct 21 Francisco Pinto Balsemão, Portuguese politician, former Prime Minister of Portugal (born 1937)
Notable Deaths 2024 Oct 21 Mimi Hines, Canadian singer and comedian (born 1933)
Notable Deaths 2023 Oct 21 Bobby Charlton, English footballer and manager (born 1937)
Notable Deaths 2023 Oct 21 Bobi, Portuguese dog (born 1992)
Notable Deaths 2023 Oct 21 Bill Hayden, Australian politician, 21st Governor General of Australia (born 1933)
Historical Events 2021 Oct 21 A shooting occurs on the set of the film Rust, in which actor Alec Baldwin discharged a prop weapon which had been…
Notable Deaths 2021 Oct 21 Bernard Haitink, Dutch conductor and violinist (born 1929)
Notable Deaths 2020 Oct 21 Frank Bough, English television presenter (born 1933)
Historical Events 2019 Oct 21 Thirty people are killed in a fiery bus crash in western Democratic Republic of the Congo.
Historical Events 2019 Oct 21 In Canada, the 2019 Canadian federal election ends, resulting in incumbent Prime Minister Justin Trudeau remaining in…
Historical Events 2018 Oct 21 A passenger train derails in Yilan County, Taiwan, killing 18 people and injuring 187.
Notable Deaths 2015 Oct 21 France Bučar, Slovenian lawyer and politician (born 1923)
Notable Deaths 2015 Oct 21 Marty Ingels, American actor (born 1936)
Notable Deaths 2015 Oct 21 Norman W. Moore, English conservationist and author (born 1923)
Notable Deaths 2015 Oct 21 Sheldon Wolin, American philosopher, theorist, and academic (born 1922)
Notable Deaths 2014 Oct 21 Ben Bradlee, American journalist and author (born 1921)
Notable Deaths 2014 Oct 21 Nelson Bunker Hunt, American businessman (born 1926)
Notable Deaths 2014 Oct 21 Mohammad-Reza Mahdavi Kani, Iranian cleric and politician, Prime Minister of Iran (born 1931)
Notable Deaths 2014 Oct 21 Edith Kawelohea McKinzie, Hawaiian genealogist, author, and hula expert (born 1925)
Notable Deaths 2014 Oct 21 Gough Whitlam, Australian lieutenant, lawyer, and politician, 21st Prime Minister of Australia (born 1916)
Notable Deaths 2013 Oct 21 Bud Adams, American businessman (born 1923)
Notable Deaths 2013 Oct 21 Gianni Ferrio, Italian composer and conductor (born 1924)
Notable Deaths 2013 Oct 21 Rune T. Kidde, Danish author, poet, and illustrator (born 1957)
Notable Deaths 2013 Oct 21 Colonel Robert Morris, American singer-songwriter and drummer (born 1954)
Notable Deaths 2013 Oct 21 Major Owens, American librarian and politician (born 1936)
Notable Deaths 2013 Oct 21 Tony Summers, Welsh swimmer (born 1924)
Notable Deaths 2013 Oct 21 Oscar Yanes, Venezuelan journalist and author (born 1927)
Notable Deaths 2012 Oct 21 Yash Chopra, Indian director, producer, and screenwriter (born 1932)
Notable Deaths 2012 Oct 21 Antoni Dobrowolski, Polish educator (born 1904)
Notable Deaths 2012 Oct 21 Jaroslav Kozlík, Czech volleyball player and educator (born 1907)
Notable Deaths 2012 Oct 21 Alf Kumalo, South African photographer and journalist (born 1930)
Notable Deaths 2012 Oct 21 George McGovern, American historian, lieutenant, and politician (born 1922)
Historical Events 2011 Oct 21 Iraq War: President Barack Obama announces that the withdrawal of United States troops from Iraq will be complete by…
Notable Deaths 2011 Oct 21 Hikmet Bilâ, Turkish journalist and author (born 1954)
Notable Deaths 2011 Oct 21 Tone Pavček, Slovenian poet and author (born 1928)
Notable Deaths 2010 Oct 21 A. Ayyappan, Indian poet and translator (born 1949)
Historical Events 2007 Oct 21 Finnish race drivers Kimi Räikkönen of Scuderia Ferrari won the Brazilian Grand Prix in Formula One. With this result,…
Notable Deaths 2007 Oct 21 Paul Fox, English singer-songwriter and guitarist (born 1951)
Notable Deaths 2006 Oct 21 Sandy West, American singer-songwriter and drummer (born 1959)
Historical Events 2003 Oct 21 Images of the dwarf planet Eris are taken and subsequently used in documenting its discovery.
Notable Deaths 2003 Oct 21 Louise Day Hicks, American politician (born 1916)
Notable Deaths 2003 Oct 21 Luis A. Ferré, Puerto Rican engineer and politician, 3rd Governor of Puerto Rico (born 1904)
Notable Deaths 2003 Oct 21 Elliott Smith, American singer-songwriter and guitarist (born 1969)
Notable Deaths 2002 Oct 21 Edward J. Mortola, American academic and president of Pace University (born 1917)
Notable Deaths 1999 Oct 21 Lars Bo, Danish author and illustrator (born 1924)
Notable Deaths 1999 Oct 21 Ahmet Taner Kışlalı, Turkish political scientist, lawyer, and politician (born 1939)
Notable Deaths 1998 Oct 21 Francis W. Sargent, American soldier and politician, 64th Governor of Massachusetts (born 1915)
Notable Deaths 1996 Oct 21 Georgios Zoitakis, Greek general and politician (born 1910)
Notable Births 1995 Oct 21 Cameron Burgess, Scottish-Australian footballer
Notable Births 1995 Oct 21 Doja Cat, American rapper, singer and songwriter

This article draws on content from Wikipedia, available under CC BY-SA 4.0.

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