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Vera Rubin, who found evidence that dark matter exists, died at the age of 88 by Circa News

Vera Rubin, the pioneering astrophysicist who helped discover powerful evidence to prove the existence of dark matter, has died at the age of 88. 

Allan Rubin, her son, confirmed that his mother died Sunday night of natural causes. 

Rubin, a Philadelphia native, had been living in the Princeton area.

Swiss astrophysicist Fritz Zwicky proposed the existence of dark matter in the 1930s but it wasn't confirmed until Rubin began her research. 

In the 1960s and 1970s, Rubin was studying the behavior of spiral galaxies when she noticed that they don't always rotate according to Newtonian gravitational theory, according to NPR

She noted that the galaxies not rotating as predicted suggested that other forces, specifically dark matter, was at work. 

Scientists now believe that dark matter, which hasn't been directly observed, makes up 27 percent of the universe. 

In addition to her scientific achievements, Rubin paved the way for other women in science. 

She was the only astronomy major to graduate from Vassar College in 1948 and then went on to enroll as a graduate student at Princeton. When she learned that women weren't allowed into Princeton's graduate astronomy program, she didn't let that stop her. 

Rubin earned her master's from Cornell University and went on to get her doctorate from Georgetown University. 

Her scientific achievements earned her numerous awards, including a National Medal of Science in 1993. Rubin was also the second female astronomer elected to the National Academy of Sciences. 

The Associated Press contributed to this report. 

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