Cecilia Payne-Gaposchkin - The Star Discoverer

Dr. Cecilia Payne-Gaposchkin discovered the composition of stars.

Cecilia was raised by her mother, Emma, who noticed Cecilia’s talent for both music and science. Emma enrolled her at St. Paul’s Girls’ School, one of the few schools at the time that allowed girls to study math and science.

At St. Paul’s, Cecilia grew fascinated with science. She later won a full scholarship to Newnham College at the University of Cambridge, where she studied botany, physics, and chemistry. Even though Cambridge did not award full degrees to women, Cecilia threw herself into her studies. At first, she wanted to study plants, but after one year she switched to physics. In many classes, she was the only woman. University rules forced her to sit in the front row, and she was often teased, but she didn’t give up.

Her love for astronomy began after hearing a lecture by the astronomer Arthur Eddington. He described his test of Albert Einstein’s theory of relativity. Cecilia later wrote that this lecture completely changed her view of the world, and she could barely sleep for days afterward. From then on, she wanted to become an astronomer. Although she couldn’t officially change her major to astronomy, she attended every astronomy lecture she could and worked on projects in her free time.

When Cecilia finished her studies at Cambridge, she was not given a degree, since women were not allowed to earn them. She soon realized that in England her only career option would be teaching at a girls’ school. But then she attended another life-changing lecture. Harlow Shapley, the director of the Harvard College Observatory, came to London to speak. With Eddington’s recommendation, Shapley invited Cecilia to Harvard, and she eagerly accepted.

At Harvard, Cecilia began studying stars. She focused on spectral classes, how starlight can be split into a rainbow of colors with a prism to reveal information about stars. Using a new idea called ionization theory, which explains how atoms gain or lose electrons, she realized that a star’s spectral class was based on its temperature, not its elements.

Her research showed that metals like silicon and carbon were present in the Sun in about the same amounts as on Earth, which was widely believed at the time. But she also discovered something shocking: stars contained far more hydrogen and helium than Earth. This meant that stars were made mostly of these two elements.

When she prepared to publish her dissertation, some male astronomers, including Henry Russell, told her not to make such bold claims. To avoid rejection, Cecilia wrote that her conclusion about hydrogen and helium was “almost certainly not real.” Her dissertation, Stellar Atmospheres, was published in 1925 and became the first PhD in astronomy ever awarded at Harvard. Years later, the famous astronomer Otto Struve would call it “the most brilliant PhD thesis ever written in astronomy.”

Ironically, Henry Russell later published his own work that reached the same conclusion as Cecilia’s. He received most of the credit for discovering the composition of stars, even though Cecilia had found it first. Cecilia never publicly criticized him, even calling his paper “epoch-making.” In her autobiography, she reflected: “If you are sure of your facts, you should defend your position.”

Cecilia stayed at Harvard, teaching students, giving lectures, and doing research. However, she was only allowed the title of “technical assistant” because Harvard would not let women be professors. Shapley fought for her, but the university president refused. It wasn’t until 1956, thirty years after her groundbreaking work, that Cecilia was finally named a full professor and chair of the Astronomy Department.

She continued to teach, research, and publish until her retirement in 1966. Her work earned many honors, including the Rittenhouse Medal and the Henry Norris Lectureship. Cecilia Payne passed away in 1979, leaving behind a legacy that inspired future generations of women in astronomy.

References:
“Cecilia Payne-Gaposchkin, 1900-1979 .” American Philosophical Society, www.amphilsoc.org/blog/cecilia-payne-gaposchkin-1900-1979.
“Cecilia Payne-Gaposchkin.” Encyclopædia Britannica, Encyclopædia Britannica, inc., 15 July 2025, www.britannica.com/biography/Cecilia-Payne-Gaposchkin.
“Cecilia Payne-Gaposchkin: Research Starters.” EBSCO, www.ebsco.com/research-starters/biography/cecilia-payne-gaposchkin.

Key words:
Innovation, Science, Courage, Perseverance, Achievement, Responsibility, Face Prejudice, Stand Up for Your Beliefs

Image Citation:
Public Domain

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