Cecilia Payne – the Stargazer

By Jaime Seltzer

Cecilia Payne was born in 1900 in Wendover, Britain. She wanted to study botany at Cambridge until she went to a lecture given by Arthur Stanley Eddington on the 1919 solar eclipse. Only four undergraduate students had won the tickets, and the only reason that Cecilia could go was that one person had dropped out at the last minute. Listening to the discoveries made by observing the eclipse, including proof of Einstein’s General Theory of Relativity was a turning point for Cecilia, whose imagination and intellect caught fire at Eddington’s words. She found that the lecture was so engraved into her imagination that she could copy parts of it down word for word.

From then on, Cecilia haunted the observatory and asked more and more questions until “the professor” was called to address Cecilia – Eddington himself. Eddington was shocked to find that the young lady had already read every book he recommended to her on science, until eventually he simply said she was welcome to make use of the observatory’s library.

Cecilia studied physics and chemistry at Cambridge alongside her initial interest, botany. However, while women were allowed to attend the University, they did not earn degrees in the same manner as men – what they received was more like a certificate of completion. Cecilia also endured some mockery for her scholarly pursuits along the way, including from Ernest Rutherford, who more than once found occasion to publicly note that she was the only young lady in his physics class.

Russell, who had convinced Payne not to emphasize her findings on helium and hydrogen, had no problem publishing similar results just a few years later; in many textbooks and articles he, rather than Payne, is credited with the discovery.

Meanwhile, an astronomy professor at Harvard named Harlow Shapley was setting up an astronomy program and had some fellowship money set aside to attract female students. He visited Cambridge and met Cecilia there, and encouraged her studies in a way that was unfamiliar and even shocking to Cecilia, who was used to reactions ranging from disinterest to outright derision from everyone but Eddington.

Cecilia knew that if she stayed at home, she would be a teacher or have no career at all. When she heard about the opportunity at Harvard, she made the unusual trip from one Cambridge to another. She was the second woman to join the astronomy program at the observatory, after Adelaide Ames. Many of the other women who worked with Shapley went on to become famous astronomers, including Annie Jump Cannon, whose system of classification of stars is still used today.

Not everyone was as open-minded about women in science as Shapley, however. His group was known as ‘Shapley’s Harem’ around campus; and shockingly, there were still no female faculty at Harvard. Perhaps this made Cecilia and the other women of the program work even harder; it is difficult to identify a time when the study of astronomy would make such leaps forward as it did at Harvard over the next several years.

Cecilia’s focus was on stars. She wanted to be able to answer a question that, so far, no one had yet been able to address in astronomy: what were stars made of? Cecilia’s background in chemistry and physics made her aware of the work on atomic spectra: that, when energy was added to an atom, an electron would jump out a bit further away from the nucleus. As that same atom lost energy, its electron would drop back into place, and it would emit its lost energy in the form of light. The color of the light the atom produced was as unique and as characteristic of that element as a fingerprint is to a person. This explained the chemistry behind colored fireworks, for example, different elements burning with different-colored flames.

Cecilia Payne

Cecilia Payne and her Women in Science playing card.

Cecilia thought that, with careful examination of the color of a star, one could determine what the star was made of, even from millions of light-years away. The issue was that stars were not made of one element, only. This made it a lot more difficult to examine the light that a star emitted and use that to determine its composition, which was part of why no one had quite nailed it, yet.

In the two years before she earned her Ph.D. (yes, you heard me – two years) she published six papers on the subject. Using Cannon’s classification system, she realized that stars were not made up of heavy elements like iron or calcium, as had been assumed, before. Instead, stars were mostly made of helium and hydrogen gases, with a very small amount of heavier elements at their core. She also showed that the different spectra stars emitted was more about whether their atoms had absorbed or emitted electrons (their ionization states) than about how much of one element or another was present, and that this directly related to temperature. Her final conclusion was that most stars are made of basically the same gases at basically the same percentages, and that Annie Cannon’s color classifications actually indicated the temperature of the star in question rather than what it was made of.

Shapley read Payne’s Ph.D. thesis and goggled at its brilliance a bit before deciding he probably ought to show it to someone else. That someone else was Henry Norris Russell, which would prove to be a rather fatal mistake for Payne’s career. Russell agreed it was the best Ph.D. thesis he’d ever read, except maybe Shapley’s. But that whole section about hydrogen and helium had to go, since it was “clearly impossible”. Payne’s readings showed that hydrogen and helium were many thousands of times more common in stars than any other element, and this so went against the thinking at the time that it seemed ridiculous.

Perhaps you can judge whether or not Payne was rolling her eyes when she added the line, “[the hydrogen and helium percentage] is improbably high, and is almost certainly not real.” By choosing to say not that her readings or her conclusions were incorrect, but that the hydrogen and helium she had observed were somehow imaginary, she appeased her Ph.D. committee members without removing the section from her paper. Later, her thesis would be called “the most brilliant Ph.D. thesis ever written in astronomy.”

It had good enough ideas to steal, certainly: Russell, who had convinced Payne not to emphasize her findings on helium and hydrogen, had no problem publishing similar results just a few years later; in many textbooks and articles he, rather than Payne, is credited with the discovery.

Cecilia earned her doctorate in 1925, becoming the first doctor to graduate from the Harvard observatory where she worked, and the first doctorate awarded in astronomy at the college as a whole. After that, she worked as Shapley’s assistant for over a decade, though really she was a professor – it was just that Harvard did not call any woman under their employ a professor of anything. None of the courses she taught made their way into the coursebook, and Payne would later discover that Shapley had managed to pay her salary through a fund marked ‘equipment’.

Perhaps it was the discovery that she had been placed in the same category as a valuable lens, but Cecilia eventually balked at having no title despite doing the same work as everyone else at Harvard. In 1938, she was awarded the title of Astronomer, but it was 1956 before she had a full professorship. Eventually, she headed up her own department at Harvard.

She married a fellow astronomer, Gaposchkin, and together they continued to do groundbreaking work. She and her assistants recorded 1,250,000 observations of variable stars – stars that twinkle! – which helped her describe the ‘life cycle’ of stars, and her study of the brightest stars in the night sky led her to discover of the shape of the Milky Way galaxy. At the time of her death, she had published over 150 papers and mentored countless students of astronomy. Her determination, her genius, and her willingness to go against the grain lit the way forward for other young women and men, too, who wished to study the stars.

References:

Cecilia Helena Payne-Gaposchkin. (2009, April 23).  In HowStuffWorks.com. Retrieved September 24, 2015 from http://science.howstuffworks.com/dictionary/famous-scientists/astronomers/cecilia-helena-payne-gaposchkin-info.htm
Soder, S., & DeGrasse Tyson, N. (2000). Cecilia Payne and the Composition of the Stars. In Cosmic Horizons: Astronomy at the Cutting Edge. N.p.: New Press – American Museum of Natural History. Retrieved September 24, 2015, from www.amnh.org/education/resources/rfl/web/essaybooks/cosmic/p_payne.html
Wayman, P. A. (2002). Cecilia Payne-Gaposchkin: astronomer extraordinaire [Electronic version]. Astronomy & Geophysics, 43(1), 1.27-1.29. doi:10.1046/j.1468-4004.2002.43127.x

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