The Maid Who Mapped the Heavens

Williamina Fleming was just supposed to help the director of the Harvard Observatory with household tasks. Instead, she changed the course of astronomy.

Photos courtesy of the Harvard University Archives.

Williamina Paton Fleming had a choice. She could let the laughter die down and allow herself to be the butt of the joke, or she could stand up, turning the joke on its head and using the moment to her advantage.

Her employer, Edward Charles Pickering, director of the Harvard College Observatory, had become so exasperated with the sloppy work of his male assistants — “computers,” as they were called in those days — he’d quipped that his “Scotch maid” could do a better job.

Williamina Fleming at the Harvard College Observatory plate stacks, circa 1900.

It was true: Fleming was his housemaid. It was also true that she had come to America from Scotland, where she’d been an excellent math student and then, beginning at 14, a student teacher. And it was true, she believed: She could do a better job. While the personal circumstances that had led her to take on domestic work had been less than ideal, she had been thrilled to be working in the house of the Observatory director, in proximity to the most productive and groundbreaking astronomy research lab in the country. During the past two years of Mina’s employment, Pickering, noting her aptitude for numbers and her quick mind, had even allowed her to do a little clerical work at the Observatory, outside of the housecleaning and other domestic work she performed. But she was ready for something more.

We don’t know what the 24-year-old single mother’s actual response was in that moment after the laughter subsided, whether it was a serious and bold, “Yes, I can do a better job,” whether she met his frustrated, sarcastic suggestion with wit, whether she waited until later and approached him privately, quietly, after the workday was over; we don’t even know for sure whether the “so easy my maid could do it” story of Pickering’s reported pique is a faithful account or mere Harvard legend. What we do know is that in 1881, Mina Fleming took the opening her boss offered. It may have been suggested as a joke, but to her it was the opportunity of a lifetime, and in taking it she helped Pickering change the history of astronomy in America — and the opportunities available for women in that discipline — forever.

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Mina had initially taken the position of housemaid out of necessity: Shortly after moving to America in 1878, her husband, James, left her. She was 22, in a new country, abandoned — but not alone. She was pregnant. It’s not clear whether Pickering was aware of her condition when he hired her, but it quickly became obvious. What also became obvious to him was that Mina was industrious, dependable, highly attentive to detail, good with numbers, and in possession of a startling natural intellect. He invited her to work as a part-time copyist in addition to her domestic duties, and when she insisted upon traveling back home to Scotland for the birth of her baby, Pickering allowed her to return to her job upon her return. It is perhaps out of gratitude for this consideration, and her general esteem for her boss, that she named her son Edward Charles Pickering Fleming.

Mina wasn’t the first woman to work in Pickering’s lab. The Harvard College Observatory, founded in 1839, was in the beginning the province of men, young physicists and astronomers whose passion for the emerging science of stellar photography kept the Observatory running despite the constant plague of poor funding. But women were allowed to volunteer as “observers,” and several applied to be student assistants. In 1875, a year before Pickering was appointed as its fourth director, the Observatory admitted three women as staff members, working as computers. At first, the women worked for free; eventually, by the time Mina was hired, they were awarded a salary of 25 cents an hour — roughly half that of the male computers.

Fleming, middle rear, and Edward Pickering, left, observe the female computers staff at the Harvard College Observatory, 1891.

Pickering had long been a supporter of women as amateur astronomers, and he believed that their participation in scientific research could provide them with opportunity previously denied their gender.

“The criticism is often made by the opponents of the higher education of women that, while they are capable of following others as far as men can, they originate almost nothing, so that human knowledge is not advanced by their work,” Pickering wrote. “This reproach would be well answered could we point to a long series of such observations … made by women observers.”

He had also struggled since the beginning of his tenure as director of the Observatory with funding. (Ironically, the Observatory’s most enduring source of funds was due to the largesse of a woman: Mary Anna Draper, who established a memorial fund for her husband, the astronomer Henry Draper, that subsidized Pickering’s research.) And so the hiring of women was a boon both financially and scientifically. As he wrote in one of his annual reports on the state of the Observatory, the women computers were “capable of doing as much and as good routine work as astronomers who would receive much larger salaries. Three or four times as many assistants can thus be employed.”

When Pickering officially hired Mina as a computer in 1881, she was one of a handful of women computers at the lab, and the only one at that time with no scientific education. But that proved not to be a problem. She was a fast learner. She began by assisting Pickering with photometry, the process of measuring the brightness of stars, deciphering his notations, hastily scribbled in the dark of night as he and his assistants peered through telescopes, and then applying formulas to the notations he’d made during those nocturnal observations about the stars in order to calculate their magnitude.

Over the next few years, Pickering pioneered a new approach to photometry using photography, rather than purely direct observation, as a way to evaluate the brightness of stars. Photographs taken via telescope were developed on glass plates, about 8 by 10 inches. The stars appeared as tiny gray or black dots on the glass, and each plate was set on a special stand, which was designed to tilt the plate back slightly, with a mirror at the base of it that could capture daylight and reflect it up through the glass, illuminating the transparent plate.

Then, a computer would use a magnifying glass to examine the plate up close, enlarging the hundreds of spectra, or stars, on the plate, many of them only a half a centimeter across. With the magnifying glass, it was possible to discern tiny dark lines seemingly emanating from the bright pinpoints of stars, like a grayscale rainbow. These spectral lines were a kind of signature, indicating the presence of elements like hydrogen, iron and calcium, among others. Certain kinds of stars had certain kinds of patterns, making it possible to identify and classify them based on those patterns. By examining the plates in this way, it was also possible to note the relative brightness of stars to other stars, which was a way of determining the distance between them, as well as to analyze the pattern of tiny lines that held clues to their chemical compositions and to chart their coordinates. All of this helped to better define the immense expanse and scope of our universe.

Fleming, right, examines a glass plate at the Harvard College Observatory, 1891.

Pickering trained another female computer, Nettie A. Farrar, in how to measure spectra on the plates. In 1886, Farrar prepared to leave her job in order to be married, and Pickering named Mina as her replacement. Mina’s father had been a photographer, the first person in her home town of Dundee, in fact, to be proficient in daguerreotypy, so Mina felt particularly drawn to photography and well suited to the task of evaluating fields of stars on glass plates. Farrar trained Mina, initiating her in the art of measuring stellar spectra, and then Mina took over. She ultimately became responsible for not only measuring and cataloging stars and publishing the Observatory’s annual review but also for hiring, managing and training the women computers.

Early on, Mina showed a talent for discovering variable stars — stars that varied in their brightness, sometimes over periods of days or weeks, sometimes in a matter of hours. When she first began her work as a computer, there were known to be just under 200 variable stars. Within a decade at the Observatory, Mina and her fellow computers had recognized 100 more, many of them personally identified by Mina while analyzing the spectral plates. Her work poring over those plates, discovering, identifying and classifying the stars, resulted in the 1890 publication of the first Draper Catalogue of Stellar Spectra, which listed the brightness, position and type of 10,351 stars.

By 1893, thanks to Mina’s initiative and Pickering’s encouragement, there were 17 women computers working for the observatory, totaling nearly half of all of the employees. These women were sometimes referred to by men in the scientific community outside of the Observatory — derisively, and perhaps a bit jealously — as Pickering’s Harem.

There were theories about why women were so well suited to the computing done in his Observatory. The work was repetitive, and men, being more intelligent, would naturally become bored with it and thus make more mistakes; women were more inclined to that kind of painstaking, meticulous work, and they weren’t used to being paid anything at all for it, so they would be grateful for the chance to do it.

But what Pickering — and Fleming — saw was that the women who applied were eager. Eager to work, eager for intellectual excitement, eager to make a difference, eager for the chance to make a contribution to science. This made them ideally suited to the kind of research the Observatory required: close, patient observation of the heavens, in search of patterns, in search of discoveries. And they did make discoveries: not only new stars and new kinds of stars but also new ways of thinking about the stars, and new ways of measuring the distances between them and determining their trajectories.

Edward Pickering with the Harvard Observatory female computers, circa 1911. Photo courtesy of the Center for Astrophysics | Harvard & Smithsonian, Photographic Glass Plate Collection.

Mina remarked on this fact when she spoke at the Congress of Astronomy and Astro-Physics in Chicago that year, quoting from her paper “A Field for Women’s Work in Astronomy,” in which she made a case for women in science and shared the work being done by women at the Observatory:

“While we cannot maintain that in everything woman is man’s equal, yet in many things her patience, perseverance, and method make her his superior. Therefore, let us hope that in astronomy, which now affords a large field for woman’s work and skill, she may, as has been the case for several other sciences, at least prove herself his equal.”

In 1899, Mina was appointed the first Curator of Astronomical Photographs, making her the first woman to hold an official title at the Observatory, or anywhere at Harvard University. She enjoyed this work, but she became frustrated by the requirement of juggling the more academic parts of her job — editing, managing the computers, verifying their work, preparing papers for publication — with the work she truly enjoyed. She wrote in her journal from around that time:

“Looking after the numerous pieces of routine work which have to be kept progressing, searching for confirmation of objects discovered elsewhere, attending to scientific correspondence, getting material in form for publication, etc., has consumed so much of my time during the past four years that little is left for the particular investigations in which I am especially interested. …. If one could only go on and on with original work, looking for new stars, variables, classifying spectra and studying their peculiarities and changes, life would be a most beautiful dream.”

She also struggled with the double-shift of being a working single mother, writing a complaint about her college-aged son that modern mothers might well recognize:

“My home life is necessarily different from that of other officers of the University since all housekeeping cares rest on me, in addition to those of providing the means to meet their expenses. My son Edward, now a junior in the Mass. Inst. of Technology, knows little or nothing of the value of money and, therefore, has the idea that everything should be forthcoming on demand.”

Her journals also record her discussions with Pickering about the disparity in salary between the men and women at the Observatory:

Harvard College Observatory buildings, Cambridge, circa 1890–1920.

“I had some conversation with the Director regarding women’s salaries. He seems to think that no work is too much or too hard for me, no matter what the responsibility or how long the hours. But let me raise the question of salary and I am immediately told that I receive an excellent salary as women’s salaries stand. … Does he ever think that I have a home to keep and a family to take care of as well as the men? But I suppose a woman has no claim to such comforts. And this is considered an enlightened age!”

Mina’s seemingly endless industriousness was rewarded in 1906, when she was elected to the British Royal Astronomical Society, the first woman working in America to be given that honor.

In 1911, at age 54, Mina died from pneumonia. In her 30 years working as a computer at the Observatory, she had developed a new classification system for over 10,000 stars and had discovered 10 novae, 310 variable stars, the 94 Wolf-Rayet stars, and 52 nebulae, including the Horsehead Nebula. She was credited, along with Pickering and another astronomer, Henry Norris Russell, with discovering the type of star known as the white dwarf.

She had also raised a child, Pickering’s namesake, who grew up to become an engineer. And she was instrumental in hiring nearly 40 women at the Observatory, beginning a long lineage of American women in astronomy.

Several of the women working under Mina went on to accomplish truly outstanding work that is still relevant today: Annie Jump Cannon improved upon Fleming’s original catalog system and developed the Harvard Classification System for classifying stars; students today still learn a mnemonic device to remember the order of star temperatures she devised (OBAFGKM, which for years was expanded to “Oh, Be A Fine Girl, Kiss Me,” though in recent years more modern mnemonics have been suggested, including “Only Boys Accepting Feminism Get Kissed Meaningfully”). Henrietta Swan Leavitt, another trainee of Mina’s, made a major discovery about the relation between a variable star’s luminosity and its period, or the time it took for the star to undergo a full cycle of variation in its brightness. This came to be known as Leavitt’s Law and was used by Edwin Hubble to prove that the universe is expanding.

Portrait of Williamina Paton Fleming, c. 1890. Photo courtesy of the Special Collections, Fine Arts Library, Harvard University.

The Royal Astronomical Society noted Mina’s passing in their monthly notice in February 1912: “As an astronomer, Mrs. Fleming was somewhat exceptional in being a woman; and in putting her work alongside that of others, it would be unjust not to remember that she left her heavy daily labours at the observatory to undertake on her return home those household cares of which a man usually expects to be relieved. She was fully equal to the double task, as those who have had the good fortune to be her guests can testify.”

Pickering also acknowledged the “severe loss” the Observatory faced in her passing, and the extra administrative load he had required of her, writing in that year’s annual report, “Mrs. Fleming’s record as a discoverer of new stars, of stars of the fifth type, and of other objects having peculiar spectra, was unequalled. Her gifts as an administrative officer, especially in the preparation of the Annals, although seriously interfering with her scientific work, were of the greatest value to the Observatory.”

Annie Jump Cannon succeeded Mina as Curator of Astronomical Photographs, and the line of women holding that position at Harvard continues to this day. After Cannon retired in the 1940s, there was a time where there was no curator, but in the 1960s, a woman named Martha Hazen took over as custodian of the glass plates. In 2002, she retired and appointed Alison Doane, who played a pivotal role in starting the plate digitization project, beginning the process of shifting the physical archive of some 500,000 glass plates to a digital database. Lindsay Smith Zrull took over as Curator of Astronomical Photographs shortly before Doane’s death in 2017. Zrull helped digitize and catalog the plates, and in addition discovered more than 2,500 notebooks, journals and logs from the women computers of the early days of the Observatory.

Zrull also worked with librarians at the Harvard-Smithsonian Center for Astrophysics to begin scanning and digitizing those records, preserving the work of these women in an effort called Project PHaEDRA (Preserving Harvard’s Early Data and Research in Astronomy). The process of deciphering and digitizing their work is ongoing, with volunteers closely analyzing the pages and pages of records, looking for vital information in much the same way as Mina and the other women computers once pored over photographic plates, interpreting the data of the stars.

In 1907, a few years before she died, Williamina Paton Fleming applied successfully for U.S. citizenship. The form assumed a male applicant: There was a space to list “Wife,” but not “Husband.” Mina crossed out “Wife” and wrote in “Husband,” noting her former husband’s name and identifying him as “deceased.”

On the citizenship form, there was also a space left blank for occupation, and in this she wrote one word.