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Francis G. Pease's interferometer at Mount Wilson Observatory is the first to measure the diameter of a star, Betelgeuse

The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.

The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,710-foot (1,740-meter) peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.

The observatory contains two historically important telescopes: the 100-inch (2.5 m) Hooker telescope, which was the largest aperture telescope in the world from its completion in 1917 to 1949, and the 60-inch telescope which was the largest operational telescope in the world when it was completed in 1908.

Historical Significance

The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.

Events Before

  1. Battle of Jutland: British naval commander David Beatty is promoted to full admiral

    The Battle of Jutland (German: Skagerrakschlacht, lit. 'Battle of the Skagerrak') was a naval battle between Britain's Royal Navy Grand Fleet, under Admiral Sir John Jellicoe, and the Imperial German...

  2. J. D. Salinger is born

    J. D. Salinger, American author, known for american author, was born on 1919-01-01.

  3. German Workers' Party forms, precursor to the National Socialist German Workers' Party (Nazi)

    The German Workers' Party (German: Deutsche Arbeiterpartei, DAP) was an obscure far-right political party established in the Weimar Republic after World War I.

  4. The 18th Amendment to the US Constitution, authorizing the prohibition of alcohol, is ratified by a majority of US state

    The 18th Amendment to the US Constitution, authorizing the prohibition of alcohol, is ratified by a majority of US states

  5. German theoretical physicist Physicist Albert Einstein (39) divorces Serbian physicist and mathematician Mileva Marić (4

    German theoretical physicist Physicist Albert Einstein (39) divorces Serbian physicist and mathematician Mileva Marić (43) after 16 years of marriage

Events After

  1. Republic of Turkey is declared from the remnants of the Ottoman Empire

    Turkey, officially the Republic of Türkiye, is a country mainly located in Anatolia in West Asia, with a smaller part called East Thrace in Southeast Europe.

  2. Charlie Chaplin releases his first full-length feature, "The Kid," a silent film starring Charlie Chaplin and 6-year-old

    Charlie Chaplin releases his first full-length feature, "The Kid," a silent film starring Charlie Chaplin and 6-year-old Jackie Coogan

  3. Actor Jack Haley (22) weds Florence McFadden

    Actor Jack Haley (22) weds Florence McFadden

  4. Comedian Oliver Hardy (29) marries actress Myrtle Reeves (24)

    Comedian Oliver Hardy (29) marries actress Myrtle Reeves (24)

  5. French army captain, and future president, Charles de Gaulle (30) weds Yvonne Vendroux (20) in the Notre-Dame de Calais

    French army captain, and future president, Charles de Gaulle (30) weds Yvonne Vendroux (20) in the Notre-Dame de Calais church

More from the 1920s

birth

Isaac Asimov is born

Isaac Asimov, American writer and biochemist, known for american writer and biochemist, was born on 1920-01-02.

birth

Charlie Munger is born

Charlie Munger, American businessman, known for american businessman, was born on 1924-01-01.

birth

Vernon L. Smith is born

Vernon L. Smith, American economist and nobel laureate, known for american economist and nobel laureate, was born on 1927-01-01.

Byelorussian Communist Organization is founded as a separate party

The Byelorussian Communist Organisation was a communist group in Belarus, led by Usievalad Ihnatoŭski.

Frequently Asked Questions

What happened on December 13, 1920?
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,710-foot (1,740-meter) peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observatory contains two historically important telescopes: the 100-inch (2.5 m) Hooker telescope, which was the largest aperture telescope in the world from its completion in 1917 to 1949, and the 60-inch telescope which was the largest operational telescope in the world when it was completed in 1908.
Why is Francis G. Pease's interferometer at Mount Wilson Observatory is the first to... significant?
The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States.

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December 13 in HistoryYear 1920