The astronomer who discovered what stars are made of almost went unrecognized for her work

If you asked an average person to name influential astronomers in history, Cecilia Payne-Gaposchkin likely wouldn't be among them. But there's an argument to be made that she should be a household name. She's the reason we know what stars are made of, but gender bias nearly kept the astrophysicist from gaining the recognition she deserved.

When 25-year-old Cecilia Payne put forth her thesis saying that stars were mostly hydrogen and helium in 1925, it went against the scientific consensus that stars were composed of the same elements as planets. Her breakthrough research proved that hydrogen, the simplest atom, was one of the most fundamental building blocks of the entire cosmos—a foundational fact that informs space research to this day. So why isn't she more familiar to us?

A gifted scientist from childhood

Payne-Gaposchkin proved to be a gifted scientist from an early age, and her parents made sure she had the best science education they could provide in her home country of England. At 19, she entered University of Cambridge on scholarship and soon fell in love with physics. But women in science were expected to study botany, and she soon found herself being humiliated as the only woman in a physics class taught by Nobel Prize winner Ernest Rutherford, a renowned pioneer in atomic and nuclear studies. “At every lecture [Rutherford] would gaze at me pointedly…and would begin in his stentorian voice: 'Ladies and gentlemen,'" she wrote in her autobiography. "All the boys regularly greeted this witticism with thunderous applause [and] stamping with their feet…at every lecture I wished I could sink into the earth. To this day I instinctively take my place as far back as possible in a lecture room.”

She found a more supportive mentor in astrophysicist Arthur Eddington, but even he told her she wouldn't have opportunities in England as a female astronomer after she finished at Cambridge. He did, however, offer her a glowing recommendation to work with Harlow Shapley, director of the Harvard College Observatory, who was starting up a graduate studies program. In 1923, Payne moved to the U.S. to continue her studies at Harvard.

A brilliant thesis thwarted

However, she faced limitations due to her sex there as well. Women played a significant role at Harvard, largely in the role of human computers. In analyzing spectral data that Harvard computers had painstakingly collected and organized, Payne-Gaposchkin discovered that spectra from ionized atoms, like those in the hot outer atmosphere of stars, differed from neutral atoms of the same kind. Combining what she gleaned from her data analysis with a previously untested theory from Indian physicist Meghnad Saha, she produced her thesis, Stellar Atmospheres.

Cecilia Payne (top row, second from the left) with other women working at Harvard in 1925Harvard University Archives

Part of her thesis was well-received, but the part in which she discovered helium was 1000 times more abundant and hydrogen was 1,000,000 times more abundant in the stars than previously thought hit a bump. Princeton Observatory director Henry Russell, an outside examiner of her thesis, thought the idea that the Sun was made almost entirely of hydrogen simply couldn't be true. "It is clearly impossible that hydrogen should be a million times more abundant than the metals,” he wrote to her. She would not be able to have her thesis accepted without Russell signing off on it, so she did was she felt she must. In her final draft, she wrote, “The enormous abundance derived for [hydrogen and helium] is almost certainly not real,” essentially disowning that part of her research result.

Proven right but without recognition

Ironically, Russell himself would prove her right just a few years later. In 1929, Russell published his own research, which had the same conclusion as Payne-Gaposhckin's but by a different method. He cited Payne-Gaposchkin’s work, noting that his results agreed with hers. However, he did not state that he had originally rejected her (correct) thesis. Later, Payne-Gaposhckin expressed regret at waffling on her findings. "I was to blame for not having pressed my point," she wrote in her autobiography. "I had given in to Authority when I believed I was right…I note it here as a warning to the young. If you are sure of your facts, you should defend your position.”

Payne-Gaposhckin continued research work and taught graduate courses, though she wasn't given the title of "professor" or even "instructor." Officially, she was Shapley's "technical assistant." When Shapley approached the dean and president of Harvard to have that changed, both refused. The president, Abbot Lawrence Lowell, said that Miss Payne “would never have a position in the University as long as he was alive."

Roadblock after roadblock simply because she was a woman

The biases against Payne-Gaposhckin as a woman stymied her again and again, but she persevered in her life's work. She technically earned the first Ph.D. in astronomy at Harvard, but it was officially awarded by Radcliffe, the women's college because Harvard's physics department chair refused to accept a woman candidate. She was paid poorly for her work and wasn't given any titles or positions that a man of her ability and qualifications would have been given. When Shapley launched the full department of astronomy at Harvard, he wanted Payne-Gaposchkin—his best researcher—to serve as its first chair, but he knew Lowell wouldn't allow it, so she was passed over for a male astronomer.

Despite teaching and researching, writing books and hundreds of papers, it would be three decades before Payne-Gaposchkin's contributions to astrophysics were recognized. She basically had to wait for the men with strong anti-woman biases to step down or retire and for men who saw and honored her brilliance to give her the recognition she had rightfully earned.

Finally a full professor and department chair

On June 21, 1956, The New York Times reported, “Harvard University announced today the appointment of Dr. Cecilia Payne-Gaposchkin as Professor of Astronomy. She is the first woman to attain full professorship at Harvard through regular faculty promotion.” A few months later, she also became the first woman to head a department at Harvard as she became chair of the astronomy department. And a few years later, in 1960, distinguished astronomer Otto Struve referred to Payne-Gaposchkin's Stellar Atmospheres as “the most brilliant Ph.D. thesis ever written in astronomy.”

The sun and other stars are primarily made of hydrogen and helium.Photo credit: Canva

Perhaps most impressive is that, through all of her hard work and continuous road blocks due to her gender, Payne-Gaposchkin managed to marry a fellow astronomer and raise three children. As physicist and author Sidney Perkowitz writes in Physics World writes in Physics World:

"In some sense, one might say she 'had it all' in combining science with family and children, but getting there was unnecessarily difficult and gruelling because of bias against women. She became a full professor only at age 56, much later than a man with similar achievements would have reached that status, and after being passed over for advancement, which must have taken a psychological toll. Only a person with exceptional drive and persistence, along with scientific ability, could have endured until final recognition."

In 1976, three years before she died, the American Astronomical Society awarded Payne-Gaposchkin the prestigious Henry Norris Russell Prize. In her acceptance lecture, she said, “The reward of the young scientist is the emotional thrill of being the first person in the history of the world to see something or to understand something.”

Thank you, Dr. Payne-Gaposchkin, for not only being the first person on Earth to see what stars are made of, but for doing so in the face of all the obstacles unnecessarily placed in your path.