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)
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 (1928-07-23) July 23, 1928 (age 83)) is an American astronomer who pioneered work on galaxy rotation rates. She is famous for uncovering the discrepancy between the predicted angular motion of galaxies and the observed motion, by studying galactic rotation curves. This phenomenon became known as the galaxy rotation problem.
Vera Rubin can be seen on the BBC documentary Most of Our Universe is Missing.
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