Ladies of the Laboratory 2: How in a Few Months Late in the 19th Century One Man Who Had Little Interest in Gender Equality Hired More Female Astronomers than the World Had Ever Known
Sexism is not fully understood—even today in the most sophisticated societies. For example, there is one view that same sex education is desirable for females in that they will do better if they are not dominated by males where traditional socialization tends to pressure them into passive interactive roles that are not necessarily conducive to female optimization. Females in science have almost always had to fit into a male culture and environment.
There was one exceptional historical setting where, although males were the final controllers, women worked with other women and under female supervision and the science thrived. This one instance a female culture, scientific laboratory was so successful that females produced more science output than all the men in history. The mostly female model succeeded so well that it put itself out of existence. But more females had worked as astronomers in this one instance than in all of prior recorded history.
This is also an example of how science and technology can make enormous social changes in society as a whole, even overturning the age-old sexist bias against female scientists..
The time was the last decade of the 19th century. The place was the Harvard University Astronomical Observatory headed by professor Edward Charles Pickering, 1846-1919.
In 1824 the French had developed photography. Americans took up the new technology and became the first to use photography as a tool in Astronomy. John William Draper, 1811-1882, a chemist at City College of New York, in 1840, set up a camera and took the first astronomical photograph through a telescope—a picture of the moon which then required an exposure of 20 minutes. Ten years later, William Cranch Bond, the then Director of the Harvard Observatory took the first photograph of a star through a telescope. The technological “gold” rush was on. Thanks to a donation to Harvard for using photography in Astronomy given by the widow of John William Draper, the Harvard Observatory with its 11 inch telescope started documenting the visible universe, and towards the end of the century, there was organized documentation activity of the skies virtually every evening where weather allowed. By then, as is typical of a technological breakthrough in science, there were tens of thousands of developed, glass, photographic plates amassed at Harvard. In addition, another bequest had paid for the establishment of a Harvard telescope and observatory in Arequipa, Peru one of the best sites on Earth for astronomical observation due to the high altitude, clean air, and lack of light “pollution” from nearby cities. Photo plates started arriving from Peru to Harvard.
Up to that point, most of the effort of astronomers was concentrated on gathering data—spending endless hours looking through telescopes, making notes and drawings of what was observed “out there.” There was precious little data with which to work. The leading astronomers were those who could find something that others had not yet seen. With the new photographic technology, In just a few years, the accumulated data was enormous, and the problem in astronomy shifted from gathering data to analyzing and recording data. As is typical, after the analysis problem was solved, the need shifted to the dissemination of the findings and Harvard produced the then greatest catalogue of stars in the universe. This pattern of the development of a science, moves from the central problem and manpower starting with observation and data gathering; then shifting to analysis; and finally to information dissemination and teaching.
The method that Director Pickering had chosen to solve the analysis problem was to use graduate students and also to hire astronomers to work at the observatory as “computers.” The term at the time referred to people who would spend much of their time computing things. In the case of the glass photo plates, each star had to be identified on the glass plates and then measured and located by rulers and protractors measuring distance and angles, then using trigonometry, documenting the location of the star. As other characteristics of the stars were identified, they too would be added to the paper and pencil data base.
The work was terribly tedious, requiring sharp visual discrimination skills, a good memory, accurate, sophisticated mathematical computation, and careful transcription. However, the self image of an astronomer at the time was a man who would scan the night sky peering through the telescope, operating the complex machinery to keep the telescope pointed in the right direction and perceiving things that no one had ever before perceived. To be one of Pickering’s computers, the work was done during the day, indoors, with a group of others, and no equipment to control or photographs to take. Being a computer did not fit the self image of the male, scientist astronomer of the time.
As a result the men were not particularly productive, made many mistakes, and were clearly not excited about the work. One day Professorr Pickering was outraged over the poor quality of the work and was berating the computers and the computers’ supervisor. In his rage Pickering told them, “My Scotch maid can do this science work better than you do.”
The next day, he sacked all the men, brought in his Scotch maid and told her to hire other women, and the maid would teach them and supervise them in doing the highly technical, scientific work. Many people did not believe Pickering would do such a thing. Even after he did it, few believed that he did. After all, although the work was repetitive and tedious, ok for women in the stereotype of the day, it was also exacting, analytical, and quantitative. All in a context which required special relations—capabilities of men and certainly not women who did not “have a head for such logical compleity.” Housemaids could not do trigonometry much less teach it to others.
However, Pickering had been planning this for some time. His “Scotch maid” was a highly educated woman who had been a teacher in Scotland and emigrated because of the grinding poverty in Scotland at the time. She had learned and taught geometry and trigonometry. She was far from the typical maid. And Pickering was not thinking of training ordinary housemaids. There was The Society for the Collegiate Instruction of Women associated with Harvard. It would later be renamed as Radcliffe College. Radcliffe taught a very similar curriculum as Harvard and in some cases, the instructors were the same, especially in the sciences as there chances of finding a woman who could teach science were somewhere between slim and none. However Pickering and his “maid” knew that there were some very able women who had studied mathematics and physics. They could hire them. And instead of paying the men 50¢ a day, he could get the women to work for 35¢–about the same ratio of discriminatory differential pay that would last in America for about 100 years and many argue still exists.
Pickering’s Scotch maid, Williamina Flemming, 1857-1911, then a middle aged, mature woman, reported for work and supervised a group of bright, well-educated women who remarkably for the time, now had a chance to use their intellectual talent for anything other than teaching or nursing. Whereas some women could study physics or chemistry at the time, astronomy had been absolutely out of bounds. Astronomers spent late nights in cold dark observatories and Victorian morality of the time would not allow women to spend a night in a dark building with men. It is not clear whose tendencies toward hanky panky was suspect—the men or the women, but the reality was that women could not work in observatories at night, and night was the only time that good astronomy work could be done. As a result of celestial photography, women could work at astronomy without putting themselves in sexually compromising positions. And Edward Charles Pickering would employ more women in astronomy in the next year that probably had worked in the field in the entire history of the human race up to that point.
One of the female computers was Annie Jump Cannon, 1863-1941. She was the daughter of a wealthy, Delaware shipbuilder and state senator. She had studied at the finest girls school in Delaware, and then enrolled in Wellesley College, then and now, one of the leading women’s schools in the nation. She had a strong education in mathematics and a degree in Physics. She was interested in Astronomy and enrolled in Radcliffe for graduate work because of its proximity to the Harvard Observatory. That was what Pickering had traded his male computer force for, and for only 35¢ a day in salary .
Annie Jump Cannon quickly became the discoverer and cataloger of more stars than any person in history. She had the skills, the training, the patience, and the drive, together with the opportunity presented by tens of thousands of photographic plates. Most of the male astronomers didn’t realize what the new photographic technology would mean. Annie Jump Cannon did. She had become an expert at photography before she got to Harvard. She didn’t have to peer into telescopes, wait for good weather, bear the cold. Then spend weeks trying to confirm if what she thought she saw she really did see. She could sit comfortably in a warm office and do nothing else but discover unknown stars all day long. Over a 4 year period, Cannon had discovered and catalogued about 5,000 new stars every single month. Male astronomers, most of whom still didn’t “get it”, would spend a month of nights in the cold and discover one or two new stars. Full professors were recognized for discovering 100 different new stars in their careers. But Annie alone, using the new technology was able to contribute almost a quarter of a million stars to the data base identifying the location, color and brightness of each. At the same time she developed what would be called the Harvard Star Classification System which divided stars into 7 brightness types (O, B, A, F, G, K, M). Her system is still learned by all undergraduate astronomy students. Cannon was the first woman to be awarded an Honorary Doctorate from Oxford University, and she was awarded the prestigious Draper Gold Medal of the National Academy of Sciences. Women were suddenly astronomers. One single woman in a few years had identified more stars than all the men in history put together—not just more, but many times more than all the Astronomers since the Egyptians. Other women were performing prodigious astronomical feats and Harvard became the world center of astronomy with a group of women, supervised by a woman doing almost all of the creative scientific work. What was fascinating, in retrospect, is that although Harvard’s observatory under Pickering was vaulted to preeminence, others did not emulate the modality that Pickering was using. It was not a big secret. It was out in plain sight. Visiting male astronomy professors from the great observatories of the world all visited. They observed what Pickering was doing and saw the women. But the sexism and bias was so ingrained that they could not believe what they were seeing. Oh yes, they saw a group of women with the photo plates, but surely they were just filing them and cleaning them to prepare for the men to do the mathematics, make the critical observations and log the new information into the data base. In ancient prophetic language,
Their eyes are open but they seeist not.
But Annie Jump Cannon, wonderful astronomer that she was, never got a chance to do a more advanced type of research—the kind of theoretical and mathematical work that would allow her to make the great intellectual breakthrough that would change the insight and methods of all astronomers thereafter. The great breakthroughs. That was done by another of Pickering’s lady computers.
Yardstick of the Universe
Henrietta Leavitt, 1868-1921, walked into the Harvard Observatory as she had heard that there were opportunities for women to do astronomy research. She came from a well-to-do, prominent, Congregational Church family. Her father was the minister. Not in need of money, Henrietta volunteered her services, which offer was immediately accepted. She had graduated from Radcliffe with a strong mathematical and scientific education. After graduation, she was struck with a bad case of meningitis which made her profoundly deaf. After two years, she had recovered and although deaf, had learned to read lips and was looking for something productive to do. (It was an amazing coincidence but Annie Jump Cannon was also deaf. The two deaf women would be the most accomplished and famous female astronomers in the world.)
Leavitt was first assigned to be a computer, but she was so outstanding that soon she was asked to take on a more complex and sophisticated job and was put on the payroll. One of the advantages of the photographic plate technology was that two glass plates of the same scene taken on different nights could be placed one on top of the other and by holding them up to the light and slightly shifting their relative positions, comparisons might be made and changes discerned if the observer was very careful and perceptive. And Henrietta Leavitt seemed to be the best. What was she searching for?
Pickering asked Leavitt to try and superimpose plates on one another and see if she could detect changes in the relative brightness of particular stars on different nights. What Pickering wanted Leavitt to find was a rare kind of star called a “variable star”—one whose brightness was constantly changing. If Pickering could compare the two plates and find one out of the thousands of little white dots that was brighter on one plate than they other, they could look at all the plates for a whole sequence of evenings and determine of it was a variable star, and if so, announce it to the other astronomers world. Of the tens of thousands of stars that had been discovered and catalogued at that time, less than 2500 were documented variable starts. These stars were of particular interest, as at the time there was no reasonable explanation of why a few stars in the galaxy would be variable. What could account for that? Our sun and all other stars had slight surface events that might change the brightness slightly, but, it would take years to have instruments that would be able to measure these tiny differences. But there were a few stars which varied in brightness so much that it could be seen with the naked eye and a magnifying glass. That was Henrietta Leavitt’s task. Find variable stars!
And find them she did. Many that Leavitt found had already been scanned by other astronomers who missed them. Soon she had personally discovered 2,400 variable stars, about the total number that had been discovered by all other astronomers for 250 years since the first had been recognized. A professor at Princeton referred to her as a “variable star fiend.”
There was one particular kind of variable star in which Henrietta Leavitt became interested. These are called Cepheids. These variable stars were giant yellow stars that were named for the prototype star, Delta Cephei. This star had been discovered by an English astronomer 2 centuries earlier.
John Goodricke, 1764-1786, was an English gentleman astronomer who was the first person to note that there were a few stars which seemed to appear and disappear on different evenings—even when all the other stars seemed to be of the same brightness. Then he noticed that those particular stars, unlike other stars, changed their brightness from time to time. In 1784 he discovered Delta Cephei one of these variable stars that was very large and yellow. (There was another coincidence. John Goodricke, the discoverer of the Cepheids that Henrietta was searching for was also profoundly deaf.)
There were two things that Henrietta Leavitt catalogued for each of the Cepheids she found; she classified the brightness and the period of the variability—the time it took to go through its cycle of dimming and brightening again. Each of the Cepheids had a regular pattern of getting dimmer and brighter. Some Cepheids would complete a cycle from bright to dim and back to bright again in 10 days and others might take 20. Each Cepheid had its own period—the time of the cycle.
Brightness of stars was important but very illusory. There are two reasons that one star can appear to be brighter than another. The first is because it really is brighter, but the second is because it is closer and just appears brighter. The problem is like looking at two airplanes in the sky. One appears to be larger than the other. It might be so. But it also might be smaller, but be much closer and therefore appears to our eyes to be larger. There was then no relationship between the apparent brightness of a Cepheid and its period. But Henrietta had so much experience at looking at millions of stars that she seemed to sense a relationship, but it was only subjective, and she sought to find an objective way to examine the problem. Then she had an idea. It was one of those brilliant, creative ideas that, the minute other astronomers heard it, they slapped their head and said “of course.” This was her idea.
There was a dwarf galaxy of stars close to but different from our Milky Way galaxy. It was called the Small Magellanic Cloud. It is the farthest thing from us in the universe that can still be seen with the naked eye. It had been sighted by Ferdinand Magellan on his great voyage of exploration. It contains millions of stars. The cloud had been photographed many times by the 24 inch Harvard telescope in Peru, and Henrietta Leavitt had identified over 1700 variable stars in the cloud and found 25 different Cepheids in the Small Magellanic Cloud. Leavitt reasoned that the Cloud was quite small as galaxies go. And therefore the distance between each of the Cepheids in the cloud and the earth was essentially the same. Especially when compared with Cepheids in other galaxies. Therefore the apparent brightness of those 25 Cepheids in the cloud was a real difference in brightness. The apparent brightness was each different from the real brightness by the same factor since they were basically the same distance away.
One way of looking at Leavitt’s idea was to think of the 25 Cepheids in the same small galaxy as a formation of 25 warplanes—tankers, bombers, and fighters. The tankers look like the biggest planes, and if they are in the formation, the apparent largest size is the reality. The bombers appear to be and really are a little smaller. The fighters appear to be the smallest, and indeed they are. So as long as they are bunched up together in the same small galaxy, the apparent size is the real size, unlike the situation if the planes were scattered all over the sky. In that case a fighter might seem larger than a tanker because it might be much closer. In the case of the Cepheids, as long as they are relatively bunched up together, the apparent brightness is indicative of the real brightness.
Now at that time, there was no way known of measuring the distance to any stars or galaxies.
Read that again. No one had a clue of how to measure distances outside of our solar system. The best we could then do was measure the distance to the moon, the sun and the planets. The grand goal of astronomy at the time was finding a way to measure distances to stars and galaxies. No one had a clue how far away the nearest stars were. Astronomers the world over were looking for a yardstick for the universe. They were all waiting for the great man who would find that yardstick and lead astronomy out of its huge limitation. That was only a little over a century ago.
Leavitt then made a graph and plotted the brightness of only the bunched Cepheids in the dwarf galaxy on one axis and the period of its bright-dim cycle on the other. And there was a relationship. The brighter the Cepheid, the longer the period of time that the star would take to brighten and dim. Conversely, the longer the period, the greater the REAL BRIGHTNESS. Shortly thereafter, Leavitt with her mathematical background, developed and published the mathematical formula for the relationship, thereby enabling others to use the method as well. The Harvard Observatory published her paper in 1912. It was a huge breakthrough. Not quite all the way to measuring distances absolutely, but she had developed a method to measure them relatively.
Now what Leavitt and other astronomers could do was to look at any Cepheid in the universe and measure its period. That was easy. Then by using the Leavitt relationship between real brightness and period, the astronomer could determine the real brightness. So if the real brightness were say a 9 on a10 point scale, but the apparent brightness was only 1, that Cepheid was really far away. But if the real brightness was 9 and the apparent brightness 8, the Cepheid was pretty close. Remember at the time, astronomers could see all these stars but did not know whether the clumps were the same distance away or different distances. The relationship Leavitt discovered between the real brightness and the period of Cepheids could be used to measure the relative distance to any Cepheid in the universe., and she had single handedly found Cepheids all over the universe. The reason we say “relative” distance, is that Leavitt’s relationship was created for the Small Magellanic Cloud. So that was the unit of measure—the distance from Earth to the Small Magellanic Cloud. Lets symbolize that distance as M. The astronomer could look at any Cepheid in the universe and measure the distance in M units. One Cepheid might be 4M from the Earth. Another, 1.6M. Another 2M—twice the distance away from earth as is the Small Magellanic Cloud. The only difficulty of course was that no one knew what M was in miles, light years or any other form of common measurement. However, there had been a great breakthrough. Leavitt had created the first method of measuring relative distances. At that point Henrietta Leavitt could tell the world that one galaxy was 4 times further from earth then the other. And that the first was three times as far from the Earth as was the Small Magellanic Cloud. After over 5,000 years of mankind searching the stars, woman kind figured out how to begin to measure distances.
The general and very difficult problem of measuring distances in the universe had been reduced by Leavitt to the relatively simple problem of measuring the distance to a single place: the Small Magellanic Cloud. Once that were done, the entire structure would be in place. All distances to Cepheids could be converted from M units to light years or miles with arithmetic, and the problem would be solved. The measurement capability Leavitt had developed was much greater than just measuring the distance between Cepheids. Galaxies consisted of billions of stars. To measure the distance to a particular galaxy, all the astronomer now had to do was find a Cepheid or two inside the galaxy, measure the distance to the Cepheid and we had a very close measurement to the galaxy. More exciting still was this possibility. How large, in width, was a galaxy? No one then had any idea. Even our own Milky Way galaxy dimensions were unknown at the time, in either absolute or relative (M units). But if we could take a large galaxy and find a Cepheid at one end and another at the other end, we could then measure the distances from earth to the two ends of the galaxy. From Earth telescopes, we could then measure the angle the two ends make with the Earth. And then, using trigonometry we can calculate the distance across the galaxy. Likewise, we could measure the distance between any two galaxies. The Cepheids were the measuring points and Harriett Leavitt had provided all the men with the yardstick.
Leavitt’s great accomplishment directed an enormous amount of general astronomical effort towards a new special problem: Measuring the distance from the Earth to the Small Magellanic Cloud. Measuring M. Astronomers all over were no concentrating on that last piece of the puzzle. The very next year, the first of the measurements in light years was made by the Dutch Astronomer, Ejnar Hertzsprung, 1873-1967. He used the older parallax method (telescopic sightings from different positions and trigonometry) on the closest Cepheids and worked backwards to Leavitt’s findings. The Universe had its yardstick in absolute terms. It could now be measured.
There was one small difficulty, and that was that Hertzsprung had seriously underestimated the distance. The parallax method required very precise, but somewhat subjective and judgmental, visual, angular measurements. However, in the usual scientific process of replication, the error was soon found and better estimates given. Since then, astronomers have been able to measure star and galaxy distances in the universe.
Unfortunately in a repeat of the old story, Leavitt never got the full credit for her work that would have inured to her were she a faculty member at Harvard. Because she was only a staff member, the “standard” method that she had developed was always officially denoted as the “Harvard Standard,” not the “Leavitt Standard.” Thereafter, astronomers writing research papers using the yardstick referred to the fact that they had used the Harvard Standard to make their measurement. Many people in astronomy at the time did not even know that Harriett Leavitt or any other woman even worked at the Harvard Observatory, much less that she had developed the standard, even though Pickering published her article under her name alone. People at that time might accept that a woman could find and catalogue thousands of new stars, but it was really inconceivable that such a monumental and creative intellectual breakthrough could have been made by a very young woman. She had two credibility strikes against her. If she had been given more type theoretical research opportunities, she might have been more recognized in her own day. However, observatory Director Pickering had his objectives and his catalogue and data base of stars was the flagship product of the Observatory if not the entire university itself. No one was better at finding stars and cataloguing them than Harriett Leavitt, and Pickering promoted her to be the Head of the Department of Photographic Photometry. Now in one sense this was a great honor, especially for a staff member who did not have a doctorate and was a woman. In another sense it was a tragic assignment. An astronomer who had demonstrated this kind of creativity and brilliance ideally would just be given free rein to do creative theoretical and mathematical research, not be responsible for a then large staff (of women) in a production operation that had to be done well, but could have been accomplished by lesser minds. Leavitt, however seemed to be quite satisfied with her role, but in that role she had become a science administrator and had no opportunity to do any more real research.
Given the sexism of the time, it is hard to assess Pickering’s behavior. Without him, women would never have been given a chance to work at astronomy at all. But he was one of the first men to exploit the sexism and benefit from the lower wages for which women were willing to work. When Leavitt started doing creative science, Pickering was supportive—as long as she maintained her cataloging production rate. When she came up with major new findings, he did not try to claim credit for himself. He gave her the credit. On the other hand, he did not encourage her to submit her results to a scientific journal as most men would have insisted upon if it were their work. He may have thought that her lack of faculty status and sexism might have made journal acceptance difficult if not impossible. He did go out of his way to publish the results under her name, but as a Harvard Observatory publication, leading to the Harvard branding of the yardstick. But then he put his production needs in front of her potential research, but it is hard to assess, looking backward, how he could justify a free rein to a staff member without an academic appointment. And without a doctorate at the time, such an appointment would have been very difficult, and Pickering could not have made it if he wanted to. That was a decision of the faculty senate and the existing all male faculty.
Some scientists around the world wondered who had thought of this amazing method called the Harvard Standard. They knew that this had to have been done by a single person or two in collaboration. This type of thing could not be done be a committee. A leading Swedish mathematician found out and was about to nominate Leavitt for the Nobel Prize when he discovered that she had died. The prize is only awarded to living people, and that was the end of the effort.
After, Leavitt’s death, Pickering’s successor could not really accept the fact that this un doctored, young, female could have created the Harvard Standard alone and treated it as a Harvard team effort in which she was part of the team. In reality, Leavitt had little or no support from Harvard. He was paid for her production effort and she had to maintain that. She did her creative research “on the side.” She had no collaborators. She was too lowly for male astronomers to converse with her. Her female computers, bright as they were, were not in her league, and her deafness prevented the normal kind of scientific interchange if there were a scientist who would interact with her intellectually. She accomplished her amazing and valuable work all on her own.
In the astronomical world, Harriett Leavitt, is known not only by her remarkable method of measuring the universe, but also by the crater on the moon named after her and an asteroid was also named in her memory.
The Harvard lady astronomers had been so successful that they changed they catalogued most of the then known universe—far more than all the other world astronomers put together. They found the variable stars that were so rare. They found the Cepheids. And they, through Leavitt, made the biggest astronomical breakthrough of the decade. The male astronomers slowly “got it”. The action was not out in the observatories but with the photographic plates. The new Harvard observatory began hiring men and after a few years, there were no more women doing astronomy. The men now wanted to do that work and they had degrees and professorships. Soon, normality returned to the Harvard observatory—no women astronomers. However, Harvard never again reached the pinnacle of prestige as they had when the women were producing most of the science. And it would take another 80 years before one could visit the Harvard observatory and again find a number of women working there. With women back in the astronomy game, we may yet have a new golden age of astronomy.
Entry filed under: History, Science. Tags: Annie Jomp Cannon, astronomers, astronomy, Cepheids, female education, female scientists, Harvard, Henrietta Leavitt, mathematics, photography, Science, scientists, sexism, stars, variable starrs, Williamina Flemming, women.