In October 1923 Edwin Hubble used the 100-inch Hooker telescope at Mount Wilson to photograph the Andromeda 'nebula' and found a Cepheid variable star within it. Using Henrietta Leavitt's period-luminosity relation, he calculated a distance of nearly a million light years, far beyond the Milky Way. The result, announced publicly in 1925, ended the debate over the nature of spiral nebulae and showed that our Galaxy is only one among countless others. The universe was suddenly vastly larger than astronomers had imagined. Modern measurements put Andromeda at about 2.5 million light years.
Before and after
- 1 September 19231923 Great Kantō Earthquake
- 7 September 1923Founding of Interpol
- 16 September 1923Birth of Kuan Yew Lee
- 16 September 1923Construction of RheinEnergie Stadion
- October 1923Hubble shows that Andromeda is a separate galaxy
- 16 October 1923Founding of The Walt Disney Company
- November 1923German hyperinflation reaches its peak
- from 8 November 1923 to 9 November 1923Beer Hall Putsch
- 20 November 1923Birth of Nadine Gordimer
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The era
This moment belongs to the Modern era (1914 CE to 1945 CE), world wars and a changing world. You can also browse everything in the 20th century.