This thesis, a profile of astronomer Vera Rubin, highlights her scientific achievements, most notably the irrefutable evidence she gathered to persuade the astronomical community that galaxies spin at a faster speed than Newton’s Universal Law of Gravitation allows. As a result of this finding, astronomers conceded that the universe must be filled with more material than they can see. Scientists call this mysterious substance dark matter. This submission explains the scientific history of dark matter, its acceptance, and the current research being done to test its existence. It also mentions counter theories to the dark matter hypothesis and looks at Vera Rubin’s current work and how this research will help astronomers better understand the construction of the cosmos and its evolution.