On July 23, the U.S. House of Representatives approved H.R. 3196, the Vera C. Rubin Observatory Designation Act, which was introduced by Representative Eddie Bernice Johnson of Texas and Representative Jenniffer González-Colón of Puerto Rico (at large). If the Senate agrees, it will name the facility housing the Large Synoptic Survey Telescope the Vera C. Rubin Observatory in honor of Carnegie Institution for Science researcher Vera Cooper Rubin, who died in 2016.
As a woman astronomer working in the field of cosmology and galaxy studies, Rubin has always been a personal hero of mine. I can’t think of a more appropriate tribute to her memory and her incredible contributions to science, astronomy and future astronomers than this honor.
The text of the bill itself celebrates the milestones of Rubin’s scientific career. As a student and young professor, she studied how galaxies cluster and move inside such clusters. In 1970 she and astronomer W. Kent Ford, Jr., published measurements of the line-of-sight velocities and locations of individual ionized clouds of gas inside the nearby Andromeda galaxy (M31), showing that they were moving too fast to be gravitationally bound to the galaxy if the only matter binding it was the matter we can see (in the form of stars).
We call these kinds of observations “rotation curves,” because inside spiral galaxies such as Andromeda or our own Milky Way, the orbits of stars and gas circle the center of the galaxy inside a volume of space shaped like a disk. A typical rotation curve plots the velocities of gas clouds or stars toward or away from us as a function of distance from the center of the disk. These curves can be fit to models of where the matter is inside those orbits to work out how much matter is inside the galaxy and where it sits.
In Rubin and Ford’s paper, they did not make much of a fuss about the interpretation. By 1980 however, Rubin, Ford and the late Norbert Thonnard presented long-slit spectroscopy of a sample of 21 galaxies. They derived the rotation curves from these data, and in this, their most-cited work, and in the most cited work around this time in Rubin’s career, they boldly posited that gravity caused by something other than stars and gas must be binding the galaxies together. These observations provided some of the first direct evidence of the existence of dark matter inside of galaxies.
Later observations of clusters of galaxies and of the cosmic microwave background confirm that dark matter exists in even larger structures, and it appears to outweigh the stars and gas in the universe by a factor of about seven. Rubin investigated questions related to the nature of spiral galaxies and dark matter for most of her life. We still don’t know exactly what dark matter is made out of, but her discoveries transformed our thinking about the universe and its contents.
Although many of us astronomers thought Rubin should have won a Nobel Prize in Physics for her work in finding dark matter in galaxies, it’s not as if she went unrecognized during her life. She was a very highly regarded scientist, and she was recognized by her fellow researchers. In 1993, she was awarded the National Medal of Science, which is based on nomination by one’s peers, submitted to the National Science Foundation, and subsequent selection by 12 presidentially appointed scientists.
This award was set up by John F. Kennedy in 1962. In the category of physical sciences, it was first given to a woman—Margaret Burbidge—20 years later, after more than 60 men had received that prize. After another 10 years and more than 30 male prizewinners, Rubin won it. (If you’re wondering: yes, an additional 14 years passed and 27 more men won the prize in the physical sciences category before any other women did so.)
In 1996 Rubin was the second woman ever to receive the Gold Medal of the Royal Astronomical Society. The first woman so honored was Caroline Herschel, nearly 170 years prior. As did many women of her generation (or any of them), Rubin faced many barriers in her career simply because she was a woman. For example, as a scientific staff member of the Carnegie Institution in the 1960s, she had institutional access to the world-class Palomar Observatory in California. But she was denied access to the observatory, with the excuse that there were limited bathroom facilities.
Nevertheless, she persisted, and in 1965 she was finally allowed to observe at Palomar. She was the first woman to be officially allowed to do so. (Burbidge had gained access under the name of her husband Geoffrey.) Rubin carried on as an advocate for the equal treatment of women in science and helped many other women in their careers as astronomers. The Large Synoptic Survey Telescope, funded primarily by the NSF and the Department of Energy, will carry on her legacy and her work to study the nature of dark energy and dark matter and map out the structure of the universe as traced by billions of galaxies.
We have come a long way from the days where women weren’t allowed in the same buildings as men. But we still have a long way to travel, because it is still too easy, even in science and with our desire to avoid bias, for a man to cast doubt on the worth of a woman’s work. We also apparently have much to learn about the nature of dark matter—which may be a dark sector of dark matter particle species, for all we know so far. Because of Rubin’s pioneering work, we are all further along these journeys than we would be without her. By hearing her name and her story, along with the wonderful discoveries we all anticipate from the Vera C. Rubin Observatory, little girls everywhere can learn they, too, can contribute to our understanding of the universe.