Vera Rubin’s galaxy-rotation studies provided major evidence for dark matter.
Rubin and her collaborator Kent Ford measured how quickly stars orbit within spiral galaxies. Their observations showed that stars far from galactic centers moved much faster than expected from the visible stars, gas, and dust alone. The outer regions also remained gravitationally bound instead of flying apart.
This mismatch between visible matter and observed motion supported the idea that galaxies are embedded in massive halos of unseen matter. Rubin did not discover dark matter itself; the concept had been proposed earlier, notably by Fritz Zwicky in 1933. Her precise rotation-curve work supplied some of the strongest observational evidence for it.
Rubin faced discrimination during her career but became a leading observational astronomer. The Vera C. Rubin Observatory in Chile was named in her honor and began its major survey program in the 2020s.