When Vera Rubin enrolled in graduate school at Princeton, she learned women were not allowed in the astronomy program.

So she left and instead earned her master's degree from Cornell.

That led to a career that saw her examine more than 200 galaxies throughout the universe.

And in the process she discovered galaxies don't rotate as predicted, supporting the theory of dark matter.

Despite the fact dark matter has never been observed, Rubin determined dark mater makes up 27% of the universe.

Rubin's work in the field of astronomy earned her a variety of awards including a National Medal of Science in 1993.

Her son said she died of natural causes at her home, she was 88.

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