The official redesignation of what was formerly known as the Large Synoptic Survey Telescope (LSST) project, confirmed into law by the president of the United States on December 20, 2019, was an even more impressive tribute. Congress recognized that “Dr. Rubin and her collaborators used their observations, in conjunction with the work by earlier astronomers on the rotation of stars in spiral galaxies, to provide some of the best evidence for the existence of dark matter.” Not only that, “Dr. Rubin was an outspoken advocate for the equal treatment and representation of women in science, and she served as a mentor, supporter, and role model to many women astronomers throughout her life.” With these statements, Congress encapsulated the two intertwining strands that made Vera “a national treasure,” as Matthew Scott, president of the Carnegie Institution for Science (2014–2017), called her soon after her death.
Rubin is remembered first and foremost for her pioneering, long-term studies of spiral galaxies. Her stunning and unexpected discoveries helped to convince astronomers that dark matter is a real entity and, further, that it exists in vast quantities. Rubin never claimed that she had “discovered dark matter” as a concept, although others have mistakenly attributed discovery to her. Cosmologist Fritz Zwicky, writing in 1933, is credited as the first person to suggest there could be such a thing, because known astrophysics could provide no explanation for his observations of how galaxies are moving within their clusters. However, few people paid attention to Zwicky at the time, and the idea lay more or less fallow for almost forty years. From the mid nineteen-sixties, Rubin and her colleague Kent Ford decided to investigate a different kind of motion: how the stars and gas clouds belonging to an individual galaxy revolve around the galaxy’s center. They had no intention of searching for dark matter but, to her surprise, Rubin found compelling evidence that galaxies are immersed in vast halos of it. In fact, it emerged that some ten times more of this mysterious invisible stuff exists than all the particles of ordinary matter in stars and gas clouds put together. Rubin was a meticulous observer and processed her data with the utmost attention to detail, so eventually the truth dawned. Even the most skeptical of critics could not deny the credibility of the observational results she and Ford published, and what these facts implied, especially in the face of developments in theoretical astrophysics and radio astronomy happening at about the same time.