During March over the past few years, which is Women’s History Month, I have been featuring some notables from the world of astronomy in the column I write for the Grand Rapids Press. In past years, I have profiled Annie Jump Cannon, who unlocked key information about classes of stars through analysis of their spectra, and Henrietta Leavitt who is famous for developing the period-luminosity relationship among Cepheid Variable Stars, that would become the fundamental tool for determining distances to galaxies.
They are two standouts among the dozen or so members of an all female team assembled at the Harvard College Observatory in Cambridge, Massachusetts early in the 20th century by its legendary director, Edward Pickering. Pickering came to Harvard in 1877 and served more than 40 years as the visionary leader of its observatory.
Harvard Observatory complex around 1925
When we look back, it can be said that the group that toiled together for years was one of the most productive in 20th century astronomy, making significant contributions to unlocking key factors governing the nature and behavior of stars, the fundamental building blocks of the universe. It is one reason Harvard achieved a high profile among American astronomical research centers despite having mostly refracting telescopes considered modest compared to the big reflectors coming on online under darker skies out west.
Despite the respect Pickering and other male staff members developed for their female colleagues, they were always relegated to computational and clerical duties. They were considered “computers,” and as women deemed unfit to operate the observatory’s telescopes.
Harvard’s group of “computers” in the 1920s
What follows is an expanded version of this year’s piece, featuring someone who joined that team late in its existence but who built upon the findings of both predecessors and mentors to gain insight that would lead to groundbreaking discoveries of her own.
Cecilia Payne was born in England in 1900, and grew up with a keen interest in science and the natural world. She was unsure which direction her curiosity and intellect would take her until she became captivated by a lecture she attended featuring noted English astronomer Arthur Eddington. Eddington related how an expedition he organized to view a total solar eclipse in 1919 provided strong observational evidence in support of Einstein’s then untested General Theory of Relativity. She looked back at the experience as “a complete transformation of my world picture.”
Inspired by Eddington and his collaboration with Einstein, she went on to do graduate studies in astronomy at Cambridge University in England, but realized a PhD was not in view because women were not granted advanced degrees at Cambridge in the early 1920s.
Harvard Observatory Director Harlow Shapley
Feeling stifled in the UK, Payne sought a means to relocate to the United States to fulfill her ambitions. Her timing was good. Harlow Shapley, the soon to be famous American astronomer because his studies of globular clusters provided evidence that the sun is not located near the center of the Milky Way Galaxy, had just succeeded Pickering as director of Harvard Observatory. He, like his predecessor, realized the potential of women in astronomy, and offered to Payne a fellowship that had been established earlier by the retiring Pickering. Filled with enthusiasm, she sailed for Boston, arriving at Harvard in 1923.
Once situated, she easily integrated smoothly into the group of mostly older female “computers.” Among her new friends was the personable Annie Jump Cannon, whose amazing insight into the temperatures of stars based on variations in their spectra was being vigorously discussed. There were so many revelations, as well as mysteries, encoded within the dark lines crisscrossing the rainbow spectrum produced when starlight, gathered and amplified by a telescope, is dispersed by a prism or diffraction grating introduced into its path.
Cecilia Payne at work at Harvard Observatory around 1930
By then, the 13th Amendment giving women the right to vote had been in effect for a few years, and new windows of opportunity were slowly opening. Still, through all this, women were still considered unfit to operate the telescopes at Harvard on their own. Payne felt stifled by the inability to gather on her own the data she needed to support her percolating ideas. In succeeding years, she and her colleagues worked tirelessly to gain both the privileges, and respect they greatly deserved.
Payne became the first female graduate student at Harvard and therefore a candidate for a PhD. As a thesis, she elected to delve into the subject of the composition of stars, and what goes on deep down inside to make them shine. She could draw upon the wealth of clues contained within amazing collection of spectra captured and classified over the years by Cannon and her colleagues.
Cecilia Payne with Mentor Annie Jump Cannon (right)
She was noticed by male astronomers at Harvard and elsewhere, even prompting Lawrence Aller, who later came to Harvard for graduate work in the mid-30s before pursuing a distinguished career at the University of Michigan and University of California at Berkley, to say that he had heard Payne was “The most capable go-getter” among Shapley’s group of female grad students at Harvard. Her dissertation, published in 1925, was highly insightful. The prevailing theory at the time assumed that stars are composed of the same elements, and in the same proportions, as found on earth. But because stars are so incredibly hot, all these elements exist in a gaseous state. On our planet, the heavier materials predominate, but Payne produced evidence to suggest that is not true within stellar infernos.
She argued that hydrogen, the lightest and simplest element, could be a million times times more plentiful in the sun and other stars than on earth, and that most of the remaining 25 percent of a star’s mass is helium. All of the other 95 or so other known elements are present in merely trace amounts. Astronomers who supported established ideas, including such notables as Henry Norris Russell at Princeton, initially took issue with the upstart female astronomer’s challenge to conventional wisdom. Still, once her substantial evidence was fully digested and put to the usual scientific scrutiny, it stood up well.
The argument convinced another noted astronomer, Otto Struve, to effuse that her work was “The most brilliant PhD thesis written in astronomy to date.” It had become clear, and remains clear to this day, that hydrogen is not only by far the most abundant element in the structure of stars, but is by inference, by far the most abundant element in the universe.
Payne and her assistants were finally granted the same rights to use the telescopes as their male counterparts. They went on to make hundreds of significant observations, concentrating on variables of high luminosity, such as the Cepheids, which are most useful for determining both stellar and galactic distances. She spent her entire career at Harvard, building on the pioneer work of another of her notable female predecessors at Harvard, Henrietta Leavitt.
Despite Payne’s rising notoriety, and Harvard’s admirable record of providing opportunities for women interested in pursuing careers in astronomy, it took petitioning by Shapley to finally grant to Payne the title of “Astronomer” in 1936, more than a decade after publication of her groundbreaking thesis. Her salary was all of $125 a month. She was not promoted to a full professorship at Harvard until 1956, as she was entering the last decade of her academic career.
Ironically, Payne ended up mentoring a number of male astronomers who rose to future prominence, and she did become chairperson of Harvard’s astronomy department prior to retiring from an active career in 1966. She was, appropriately, the first recipient of the Annie Jump Cannon Prize, established to honor the pioneering “computer” who became a friend and mentor to Payne during their time together at Harvard.
Payne became a U.S. citizen in 1931 and a couple years later, while on a trip abroad to visit important astronomical centers in Europe and to revisit her homeland, she met Russian born astronomer Sergei Gaposchkin while at a conference in Germany. Gaposchkin expressed concern about growing oppression in his homeland, and war clouds gathering in Europe.
Upon her return to Harvard, Payne asked Shapley if he could find a position for him at Harvard, and then used her influence to acquire a visa. After Gaposchkin arrived, a romance blossomed between the two astronomers as they worked together. The couple married in 1934 and settled in Lexington, Massachusetts, just a short commute to the Harvard Observatory in Cambridge. From then forward, her papers, many containing still more new insight into the workings of the stars, carried the name Payne-Gaposchkin. Some were written in collaboration with her astronomer husband.
Cecilia Payne-Gaposchkin with Sergei and two children in 1940s
As I conclude this piece, I am looking at a treasured book in my personal collection, Stars in the Making, authored by Payne-Gaposchkin in 1952. It is a wonderfully clear exposé of the stellar census and prevailing ideas about the process of stellar evolution as perceived during the 1950s. She also discusses the nature of galaxies, and how her work and that of her predecessors on the luminosity of variable stars figures into the determination of their distances.
Back in the 1960s while a grad student, I had an opportunity to hear what turned out to be her farewell presentation at a meeting of the American Astronomical Society at the University of Michigan. Not yet fully aware of her remarkable stature, I missed it. I have come to regret that. Payne-Gaposchkin died in 1979 at age 80.