Records reveal hidden history of female astronomers at Yerkes Observatory

UChicago team chronicles dozens of women who worked and made discoveries in early 20th century

It all snowballed from a photo. On his first trip to the U.S. in 1921, Albert Einstein visited Yerkes Observatory, located in Wisconsin and run by the University of Chicago. Those present gathered for a photograph with the telescope.

Nearly a century later, members of a team poring over historical materials to preserve the history of the observatory stopped and looked at it in surprise.

“We said, ‘Wow—there are so many women in this photo,’” recalled Andrea Twiss-Brooks, director of humanities and area studies at the UChicago Library. “We recognized the men in the photo, but who were the women?”

Fortuitously, someone had written the women’s names on the photo. As Twiss-Brooks and colleagues investigated, poring over the records from the observatory, they found the women pictured were employees at Yerkes—and they weren’t the exception.

“I thought in 30 years there might be a handful, but we’ve located more than 100 so far,” she said.

Even more surprisingly, the records revealed they weren’t solely secretaries or “computers” who primarily solved equations. In an era when few women were able to be professional scientists, these women performed astronomical observations, analyzed data, collaborated with researchers around the world and published papers.

Fascinated, Twiss-Brooks and colleagues began a project to study the women and their roles based on the archival material from Yerkes.

The Yerkes materials, some of which are currently on display at the University of Chicago Regenstein Library in a special exhibit, are part of the legacy of Yerkes Observatory. A storied institution, Yerkes served for decades as a center of UChicago astronomical research before the university ended official operations there in 2018. In 2020 the facility was transferred to the Yerkes Future Foundation, which today operates it as a nonprofit center for learning and discovery.

But much of the archival material from Yerkes—photos, personnel records, logbooks, correspondence and more—had been transferred to the UChicago Library, where Twiss-Brooks and others began sorting through it. “We quickly recognized how rich a historical source it was,” she said.

She worked with Rich Kron, a professor emeritus of astronomy and astrophysics at UChicago who served as the director of Yerkes Observatory at one time; Kristine Palmieri, then a graduate student in history of science and now researcher at the rank of instructor with the Institute on the Formation of Knowledge; and many undergraduate students, to analyze and digitize the materials.

An observatory and an oasis

Located in southern Wisconsin on the shores of Lake Geneva, Yerkes Observatory was constructed in 1897 under the leadership of eminent UChicago astronomer George Ellery Hale. Yerkes’ handsome terra-cotta building housed the largest refracting telescope in the world, and for decades, the observatory attracted astronomers from around the globe.

The astronomers at Yerkes took thousands of images of the night sky and transferred them onto chemically treated glass plates. At the time, this was a new technology, and it was revolutionizing astronomy. For the first time, extremely precise images of the sky could be stored for future reference. For example, certain kinds of stars grow brighter and dimmer at regular rates, which you can track if you have a record over time.

Over the century Yerkes operated, scientists created more than 175,000 of these glass plates. Astronomers eventually needed larger telescopes in sites with better weather to collect good astronomical data, however, and the cutting edge of astronomy moved to mountaintops and more remote locations.

After Yerkes closed as a scientific observatory, Kron began working with students to catalog the items from the observatory—including the collection of glass plates, to digitize them and explore how they might be useful in current scientific research.

When Kron and the students looked at these glass plates and the daily logbooks, they noticed the signatures of women.

This was relatively unusual for the early 20th century. Many observatories, located in remote areas, were limited to men, either explicitly or implicitly. But the team found more than 100 women who were involved with Yerkes Observatory in some capacity.

Yerkes had several things that set it apart for women who wanted to do science. It was near a train line from a major city, Chicago, so women could travel alone easily and safely; and for decades, it had a director who was willing to hire them.

Edwin B. Frost headed the Yerkes Observatory from 1905 to 1932. An accomplished astronomer known for his work on stars called Cepheids, Frost was also a self-identified suffragist, and the team has theorized that his politics played a role in making Yerkes Observatory an unusually welcoming place for women in science.

From the letters, Twiss-Brooks and Palmieri learned that a number of these women earned graduate degrees from the University of Chicago and moved into a wide range of careers after leaving—both within academia and beyond.  

“There are these narratives about the history of women in science,” said Palmieri. “You either see a few ‘exceptional’ women, or you see women confined to doing rote work without creativity or agency. But these narratives fall apart the deeper you look.”

Who counts as a scientist?

Palmieri taught an undergraduate class in the winter of 2022-23, where students read about the history of women in science and examined the materials from Yerkes themselves. Based on their research, the students contributed exhibit items and captions to the library exhibit.

“The questions we’re asking include: Who ‘counts’ as a scientist? How is the labor of women recognized in the literature, and how is it valued in comparison to that of male scientists?” said Palmieri. “I wanted to have students deconstruct and reconstruct these terms we take for granted.”

As an astrophysicist, Kron said, his own perspective has been challenged. “When we were trying to find information on these women, I originally said, ‘OK, let’s catalog the papers these women published,’ which is how I would approach it today. But some of them don’t have published papers at all, which makes us have to rethink how we give credit to people and recognize people, because we know they were doing this work.”

The team traced the career of one female astronomer at Yerkes, Harriet McWilliams Parsons, who did her master’s and Ph.D. research at Yerkes. (She was awarded her Ph.D. from UChicago in 1921). They tracked down Parsons’ master’s thesis, which involved measuring the colors of the stars in the Pleiades.

“This was absolutely pioneering for the time,” Kron said. “And the funny thing is, that Edwin Hubble was at Yerkes doing research too and his Ph.D. thesis was published the same year. If I had to compare them I would say that Parsons’ is far superior work, and yet Hubble is the one that went on to become highly decorated.”

Parsons is one of the women discussed in the exhibit “Capturing the Stars,” which runs at the UChicago Library through the fall quarter. The displays include letters written by and to these women, as well as photos, archival footage, examples of the glass plates and the equipment they made and used every day. The Neubauer Collegium also funded a symposium coinciding with the exhibit opening, titled “Invisible Labor in Astronomy and Astrophysics.”

“This is such a rare opportunity to give these women back their voices,” Palmieri said.

The work of the research group has been made possible by the support of the Neubauer Collegium, the College Center for Research and Fellowships, the College Innovation Fund, the National Science Foundation, the Kathleen and Howard Zar Science Library Fund, the University of Chicago Women’s Board, the John Crerar Foundation, the University of Chicago Division of the Physical Sciences, and the University of Chicago Library. The research group gratefully acknowledges the Yerkes Future Foundation for their continued support of preservation work and educational outreach activities at Yerkes Observatory.