As if being a trailblazing woman in science in the 1950s weren't already challenging, Vera Rubin was severely criticized for her theories regarding the existence of dark matter. But once her evidence proved indisputable she was elected to the National Academy of Sciences as only the third female astronomer and was eventually awarded the National Medal of Science, America's most prestigious scientific accolade. This article by Maria Popova, which first appeared on her site Brain Pickings, is reposted, with her permission, in honor of International Women's Day.