1920's Astronomy

1920's Astronomy Major Achievements

Technological progress provided scientists with new and better ways to explore the solar system.

1920

Albert Michelson measures the diameter of the star Betelgeuse using a stellar interferometer. It is the first measurement of the diameter of any star other than the Sun.

Indian astronomer Meghnad Saha [b. Shaoratoli, India, October 6, 1893, d. February 16, 1956] describes ions in the solar chromosphere. He also showed that temperature is as important as elemental composition in determining a star's spectrum.

1921

Edward Arthur Milne [b. Hull, Yorkshire, England, February 14, 1896, d. Dublin, Ireland, September 21, 1950] develops an improved mathematical theory of radiation through the solar atmosphere.

Alfred Wegener argues convincingly that craters on the Moon are caused by impacts not by volcanic eruptions.

1922

Alexander Alexandrovich Friedmann [b. St. Petersburg, Russia, June 29, 1888, d. Leningrad (St. Petersburg), September 16, 1925], on the basis of Einstein's general theory of relativity, predicts that the universe must be expanding from a singularity -- the big bang -- improving on a similar prediction by Willem de Sitter and paving the way for a further revision by Lemaître.

1923

George Ellery Hale invents the spectrohelioscope, a device that permits the image of the entire disk of the Sun to be observed at one wavelength of light and that can be used to measure velocities of gases in the solar atmosphere. The key is a rapidly oscillating slit that, because of persistence of vision, enables the viewer to see the whole solar disk.

Otto Struve, Russian-American astronomer [b. Kharkov, Russia, August 12, 1897, d. Berkeley, California, April 6, 1963] presents his first paper, on a spectrographic binary star, the beginning of over 900 published papers on astronomy. Struve will discover interstellar matter, thin clouds of gas and dust between the stars, and in 1952 argue that mechanisms for planet formation must be common around stars.

1924

Edwin Hubble demonstrates that the galaxies are true independent systems rather than parts of our Milky Way system by resolving the spiral arms of the Andromeda nebula into stars.

The Henry Draper Catalog, compiled by Annie Jump Cannon and listing 225,300 stars, is published by Harvard Observatory.

Arthur Stanley Eddington formulates the mass-luminosity law for stars, relating the luminosity of a star to its mass. Eddington suggests that white dwarf stars are made up of degenerate matter in which the electrons have collapsed from their orbits, which is still believed to be true.

1925

Vesto Slipher determines the radial velocities of 41 spiral nebulae (not yet recognized fully as galaxies) from their redshifts. He finds that several spirals are moving away from the Milky Way Galaxy at speeds too fast for them to be contained within our galaxy.

Arthur Eddington concludes that the light and heat produced by stars originates from nuclear fusion.

 

ASTRONOMY RESOURCES

The Planet Jupiter - 1927
The Latest Astronomical discoveries and opinions regarding the great planet Jupiter

Pons-Winnecke Comet - 1927
The 1927 appearance was the best since Pons-Winnecke's discovery in 1819.