Vera Rubin: Opening doors to dark matter and women in STEM

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In 1965, Vera Rubin wasn’t just watching history unfold; she was making it—pioneering our understanding of the universe while shattering barriers for women in science.
Rainbow Gate Vera Rubin

1965 was a year of opening doors.

The Civil Rights Movement was gaining momentum, with the Voting Rights Act dismantling restrictions that had long kept many Americans from the polls. At the same time, the Equal Employment Opportunity Commission began challenging workplace discrimination, pushing for fairness regardless of race or gender.

Amid this wave of change, the Cold War rivalry between the U.S. and the Soviet Union ignited a surge of interest in space exploration. NASA’s Mariner 4 provided the first close-up images of Mars, while astronaut Ed White made history as the first American to walk in space.

Carnegie Science was also reaching for the stars—this time through the lens of cutting-edge technology.

Under the leadership of Merle A. Tuve, the Department of Terrestrial Magnetism (now part of the Earth and Planets Laboratory) was on the brink of leveraging a revolutionary tool: Kent Ford’s Image Tube Spectrograph. When attached to a telescope, this instrument promised to greatly enhance the ability to detect faint celestial objects.


Kent Ford adjusts the Image Tube Spectrometer at Kitt Peak National Observatory in 1965. The spectrometer improved the efficiency of photographic detectors by over a factor 10, making it possible to take on complex observational projects like mapping the rotational velocity in galaxies. Carnegie Science donated the spectrometer to the Smithsonian National Air and Space Museum.

However, this new instrument needed to be tested. That’s where Vera Rubin comes in. 

In a world where doors were starting to open for women around the country, Rubin knocked on ours at just the right time, ready to redefine our understanding of the universe.

Vera Comes to Lunch

Rubin wasn’t yet the world-renowned astronomer we know today. She was still in the early stages of her career after obtaining her Ph.D. from Georgetown University in 1954 and spending a decade juggling teaching, researching, and building her family.

By 1964, Rubin was looking to dive back into her research. So, she made a bold decision. She decided to step away from her teaching job to focus on her passion: unraveling the mysteries of galactic movements.

“Teaching and observing and having four children was just more than I wanted to handle,” said Rubin in an interview years later.


Vera Rubin with her children Karl, David, Allan, and Judy at Bear Lake, Rocky Mt. National Park, Colorado. 
Vera Rubin with her children Karl, David, Allan, and Judy at Bear Lake, Rocky Mt. National Park, Colorado in 1961. 

In January 1965, Rubin visited her friend Bernard (Bernie) Burke, an astrophysicist at Carnegie Science. Seeking a research position—and never one to shy away from a problem—Rubin walked into his office and asked for a job outright.

Rubin later remarked that Burke seemed “as surprised as if she’d asked him to marry her.” Presumably because, at the time, the department had no women researchers on staff.

But Burke didn’t brush her off. Instead, he invited her to join the campus community lunch. Director Tuve, perhaps sensing an opportunity, asked Rubin to stand up at a blackboard and explain her work on galaxy rotation. After her presentation, she took an exceptionally fortuitous seat next to Kent Ford.


Vera Rubin was asked to give a talk about her research at the Department of Terrestrial Magnetism's community lunch, pictured here in 1963. Note the chalkboard at the back of the room, which allowed for such impromptu presentations and scientific discussions. The tradition of cooking and eating lunch together continues at the Earth and Planets Laboratory as "Lunch Club." 

“I did not know that Kent Ford had just built an image-tube spectrograph," recalled Rubin. "I mean, that was just a gift out of the blue." 

After this impromptu lunch interview, Rubin was handed a photographic plate from Kent’s work and asked if she could measure the stellar velocities. Rubin took the plate to her office at Georgetown and got to work. Less than three months later, she started her new job as the department's first female staff scientist.

The timing couldn’t have been more perfect. Rubin’s expertise in galaxy spectra and radial velocities was exactly what Tuve and Ford had been looking for. For Rubin, the untapped potential of this new imaging tube was an exciting draw. 

Rubin recalled, “Kent was anxious to test the limits of the image tube, and I was anxious to obtain new information about galaxies.”

Together, Rubin and Ford were about to sharpen the universe's focus and expose a mystery hiding in plain sight: dark matter.

Unlocking the Door to Dark Matter

In the late 1960s, Rubin’s fascination with galaxy rotation led her to focus on the neighboring Andromeda galaxy. The Rubin-Ford duo spent nights at the Lowell and Kitt Peak Observatories, making observation after observation thanks to the efficiency of the spectrograph. 

In a 2006 article in Physics Today, Rubin recalled, "Using this device on a telescope reduced the exposure time to 1/10th that of an unaided photographic plate. It was a major step forward in telescope instrumentation."

As they processed the images, they expected to see that stars were moving faster near the galaxy’s center and slowing down as they moved out toward the edges, just as Newtonian physics would predict. But the data told a completely different story.

“The surprises came very quickly,” wrote Rubin. “By the end of the first night, we were puzzled by the shape of the rotation curve.”


Vera Rubin at Kitt Peak 84-inch telescope
Vera Rubin peers through Kent Ford's Image Tube Spectrometer at Kitt Peak National Observatory in 1965.
Vera Rubin at Lowell Observatory, 69-inch [i.e., 72-inch] Telescope (Kent Ford in white helmet)
Vera Rubin and other astronomers work on a telescope at Lowell Observatory in 1965. Kent Ford can be seen with his back to the camera in a white hat.

Instead of the expected drop in speed at the galaxy’s edges, the stars seemed to all be moving at the same rate, no matter where they were in the galaxy. When they plotted the data, the curve was flat, not the steep slope they had anticipated. This “flat curve” hinted that something unseen was adding mass to the galaxy.

Rubin proposed that this missing mass was dark matter—an invisible substance that doesn’t emit light or energy. We now know this invisible material makes up more than 85 percent of the universe.

In 1970, Rubin and Ford published those initial findings on Andromeda’s flat curve, but Rubin knew she would need more evidence to understand what was going on—and to convince a skeptical scientific community. Over the next decade, the duo observed galaxy after galaxy. By 1980, they had amassed a mountain of evidence. Their culminating paper showed the flat curve phenomenon in twenty-one different spiral galaxies.


In the paper, Rubin wrote, “The conclusion is inescapable that non-luminous matter exists beyond the optical galaxy.”


Optical (dots) and radio (triangles) rotation curve data for the Andromeda galaxy M31 superimposed on the M31 image from the Palomar Sky Survey
In this graph, the optical velocities of ionized gas clouds in the Andromeda galaxy (M31) measured in 1970 by Rubin and Ford, are shown as open and filled circles. Velocities from neutral hydrogen radio observations, measured by M.S. Roberts and R.N. Whitehurst in 1975, are shown as filled triangles and remain high far beyond the limits of the optical disc. This "flat curve" beyond the limits of the optical galaxy is evidence that dark matter is adding mass to the equation.

By 1985, Rubin’s work had gained worldwide recognition. She presented her findings at the International Astronomical Union (IAU), where she argued for the reality of dark matter on a global stage.

“In a spiral galaxy, the ratio of dark-to-light matter is about a factor of 10,” she explained to the IAU. “That’s probably a good number for the ratio of our ignorance to knowledge. We’re out of kindergarten, but only in about third grade.”

Rubin’s groundbreaking research earned her a place among the scientific elite. She was elected to the National Academy of Sciences in 1981, awarded the National Medal of Science in 1993, and received the Royal Astronomical Society’s Gold Medal in 1996. Even Pope John Paul II took notice, appointing her to the Pontifical Academy for Sciences, despite her Jewish faith.

Today, her name graces an observatory, asteroid, Martian geologic formation, and countless honors in recognition of her contributions.


At Carnegie, scientists continue to build on Rubin’s legacy, probing deeper into dark matter, dark energy, and other cosmic mysteries.


Vera Rubin receiving National Medal of Science from President Clinton and Vice President Gore, White House, Washington DC
Vera Rubin receiving the National Medal of Science from President Clinton and Vice President Gore, White House, Washington DC in 1993. 

Holding the Door for Future Generations

Vera Rubin was a trailblazer in astronomy who refused to let any door stay closed to her, whether in science or society. So, it's fitting that one of the most commonly told stories about her involves the actual bathroom doors at Palomar Observatory.

At that time, the Palomar was one of the world’s most prestigious observatories. However, women had been historically barred from observing because there were no ladies' facilities. 

In 1965, Rubin became the first woman officially invited to use the observatory. Yet when she arrived, the bathroom door still said "MEN." Taking the problem in hand, she found a pen and some tape, drew a figure wearing a skirt, and affixed it to the bathroom door, declaring, "There you go; now you have a ladies’ room."

The next time she observed at Palomar, the skirted woman was gone, and so was the sign for “MEN.” 

One small moment of progress out of a lifetime of such moments, Rubin's bathroom edit highlights her resilience and humor in the face of the absurd everyday obstructions that women in science faced in 1965. It also reflects the larger changes around the nation. Just as the country was beginning to confront long-standing injustices, Rubin was busy breaking down barriers in her own field.

“Vera would stand up against injustice and prejudice whenever she could,” recalls Alycia Weinberger, a staff astronomer at Carnegie Science who worked alongside Rubin. “She was aggravated by how few women had won prizes from the American Astronomical Association and been elected to the National Academies. Every season, she would be busy in her office nominating women herself and exhorting others to do so.” 


Front row left to right: Brooke Hunter, Vera Rubin, K.E. Saavik Ford, Alycia Weinberger, Mary Horan, Kathleen Flint, Alexis Clement.  Back row left to right: Linda Warren, Alison Shaw, Katherine Kelley, Sara Seager, Lucy Flesch, Jan Dunlap.
Vera Rubin was a firm advocate for women in science and her mentorship helped guide generations of researchers. This picture of the women staff and scientists at the Department of Terrestrial Magnetism was taken in 2003.  

​​​​​​Front row left to right: Brooke Hunter, Vera Rubin, K.E. Saavik Ford, Alycia Weinberger, Mary Horan, Kathleen Flint, Alexis Clement.  Back row left to right: Linda Warren, Alison Shaw, Katherine Kelley, Sara Seager, Lucy Flesch, Jan Dunlap.

Just as 1965 was a year of opening doors across the country, Vera Rubin spent her life opening doors for future generations, ensuring that no one would have to tape a paper skirt to a bathroom door again. She helped win inclusion at the Palomar Observatory, the exclusive Cosmos Club, and she even advised the Pope advocating for more women in the Pontifical Academy of Sciences. 

Rubin passed away in 2016, but her legacy continues. Over her career, Rubin observed more than 200 galaxies, mentored generations of astronomers, and laid the groundwork for all of the dark matter research we do today. Her life is a powerful reminder that persistence can move even the toughest barriers and change the way we see the universe. 

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