In the 1970s, astronomer Vera Rubin found evidence of a hypothetical type of invisible matter now called dark matter.
She discovered that the stars at the edges galaxies moved faster than expected. Gravity calculations using only the visible matter in the galaxies showed the outer stars should have been moving more slowly. Unseen dark matter was the predicted cause of the discrepancy.
The astronomer Fritz Zwicky had previously predicted the existence of invisible matter in the 1930s following his observations of the Coma galaxy cluster.
Image: Vera Rubin measuring spectra (Emilio Segre Visual Archives/AIP/SPL)
Rubin finds evidence of invisible matter.
Vera Rubin's star velocity measurements support theory.
Measurements of the velocities of stars orbiting in galaxies made by Dr Vera Rubin in the 1970s are evidence of dark matter's existence. Dark matter is thought to provide the "extra gravity" needed to reconcile the orbits of stars with Newton's law of gravity.
Vera Cooper Rubin (born July 23, 1928) is an American astronomer. Her father, Philip Cooper, an electrical engineer, had been born in Vilnius, Lithuania as Pesach Kobchefski, and her mother, Rose Applebaum, originally came from Bessarabia. She worked for Bell Telephone Company calculating mileage for telephone lines. Rubin has an older sister named Ruth Cooper Burg, who was an administrative judge in the United States Department of Defense Rubin earned her B.A. at Vassar College and attempted to enroll at Princeton but never received their graduate catalog, as women there were not allowed in the graduate astronomy program until 1975. She instead enrolled for her M.A. at Cornell University, where she studied physics under Philip Morrison, Richard Feynman, and Hans Bethe. She completed her study in 1951, during which she made one of the first observations of deviations from the Hubble flow in the motions of galaxies. She argued that galaxies might be rotating around unknown centres, rather than simply moving outwards, as suggested by the Big Bang theory at that time. The presentation of these ideas was not well received. Rubin’s doctoral work at Georgetown University was conducted under advisor George Gamow. Her PhD thesis upon graduation in 1954 concluded that galaxies clumped together, rather than being randomly distributed through the universe. The idea that clusters of galaxies existed was not pursued seriously by others until two decades later. After her graduation Rubin taught at Montgomery County Junior College, and also worked at Georgetown University as a research assistant, and in 1965 became an assistant professor. Also in 1965, she became the first woman "allowed" to use the instruments at the Palomar Observatory. Prior to this women had not been authorized to access the facilities. In 1965 she also secured a position at the Department of Terrestrial Magnetism at the Carnegie Institution of Washington and has worked there as an astronomer since that time. She is currently a Senior Fellow at the DTM, and her work area is described as "Galactic and extragalactic dynamics; large-scale structure and dynamics of the universe."
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