The Life and Times of Dr. Vera Cooper Rubin: Astronomy Pioneer

vera rubin
Dr. Vera Cooper Rubin in 1970, working on measuring galaxy rotation rates. Vera Rubin

We've all heard of dark matter — that weird, "invisible" stuff that makes up about a quarter of the mass in the universe. Astronomers don't know what it is, exactly, but they have measured its effects on regular matter and on light as it passes through a dark matter "conglomeration". That we know about it at all is due largely to the efforts of a woman who dedicated much of her career to answering a puzzling question: Why don't galaxies rotate the velocity we expect them to?

That woman was Dr. Vera Cooper Rubin.

Early Life

Dr. Rubin came into astronomy at a time when women just weren't expected to "do" astronomy. She did study it at Vassar College and then applied to attend Princeton to further her education. That institution didn't want her, and didn't even send her a catalog to apply. At the time, women were not allowed in the graduate program. (That changed in 1975, when women were admitted for the first time). Those setbacks didn't stop her; she applied to and was accepted at Cornell University for her master's degree. She did her Ph.D. studies at Georgetown University, working on galaxy motions and mentored by the famous physicist George Gamow. Dr. Rubin graduated in 1954, writing a thesis that suggested that galaxies clumped together in clusters. It was not a well-accepted idea at the time, but today we know that clusters of galaxies most certainly do exist.

Tracking the Motions of Galaxies Leads to Dark Matter

After finishing her PhD. work in 1954, Dr. Rubin raised a family and continued to study the motions of galaxies. Sexism hindered some of her work, as did the "controversial" topic that she pursued: galaxy motions. Through much of her early career, she was kept from using the Palomar Observatory (one of the world's leading astronomy observing facilities) because of her gender.

One of the arguments made to keep her out was that the observatory didn't have the right bathroom for women. It was symbolic of a deeper prejudice against women in science, but that bias didn't stop Dr. Rubin.

She forged ahead anyway and got permission to observe at Palomar in 1965, the first woman allowed to do so. She began working at the Carnegie Institution of Washington's Department of Terrestrial Magnetism, focusing on galactic and extragalactic dynamics. Those focus on the motions of galaxies both singularly and in clusters. In particular, Dr. Rubin studied the rotation rates of galaxies and the material in them.

She discovered a puzzling problem right away: that the predicted motion of galaxy rotation didn't always match the actual observed rotation. Galaxies rotate fast enough that they would fly apart if the combined gravitational effect of all their stars was the only thing holding them together. The fact that they don't come apart was an issue. It meant that something else was in (or around) the galaxy, holding it together.

The difference between the predicted and observed galaxy rotation rates was dubbed the "galaxy rotation problem". Based on the observations that Dr. Rubin and her colleague Kent Ford made (and they made hundreds of them), it turned out that galaxies have to have at least ten times as much "invisible" mass as they do visible mass (such as stars and gas clouds).

Her calculations led to the development of a theory of something called "dark matter". It turns out that this dark matter has an affect on galaxy motions that can be measured. 

Dark Matter: An Idea Whose Time Finally Came

The idea of dark matter was not new. In 1933, Swiss astronomer Fritz Zwicky proposed the existence of something that affected galaxy motions. Just as some scientists scoffed at Dr. Rubin's early studies of galaxy dynamics, Zwicky's peers generally ignored his predictions and observations. When Dr. Rubin began her studies of galaxy rotation rates in the early 1970s, she knew she had to provide conclusive evidence for the rotation rate differences. That is why she went on to do so many observations. It was important to have conclusive data. Eventually she found strong evidence for that "stuff" that Zwicky had suspected but never proved.

Her extensive work over the following decades eventually led to the confirmation that dark matter exists.

An Honored Life

Dr. Vera Rubin spent much of her life working on the dark matter problem, but she was also well-known for her work to make astronomy more accessible to women. She fought battles to be accepted as an astronomer early in her career, and she worked tirelessly to bring more women into the sciences, as well as for recognition of their important work. In particular, she urged the National Academy of Sciences to elect more deserving women to membership. She mentored many women in the sciences and was an advocate of strong STEM education.

For her work, Rubin was awarded a number of prestigious honors and awards, including the Gold Medal of the Royal Astronomical Society (the previous female recipient was Caroline Herschel in 1828). Minor planet 5726 Rubin is named in her honor. Many feel that she deserved Nobel Prize in Physics for her accomplishments, but the committee eventually snubbed her and her accomplishments. 

Personal Life

Dr. Rubin married Robert Rubin, also a scientist, in 1948. They had four children, all of whom eventually became scientists as well. Robert Rubin died in 2008. Vera Rubin stayed active in research until her death on December 25, 2016. 

In Memoriam

In the days after Dr. Rubin's death, many who knew her, or who worked with her or were mentored by her, made public comments that her work succeeded in illuminating a part of the universe. It is a piece of the cosmos that, until she made her observations and followed her hunches, was totally unknown. Today, astronomers continue to study dark matter in an effort to understand its distribution throughout the universe, as well as its makeup and the role it has played in the early universe. All thanks to the work of Dr. Vera Rubin.