Nearly a century ago, a young woman turned astronomy on its head with a brilliant, groundbreaking discovery that opened the floodgates to many more discoveries in the field of astrophysics.
One hundred years ago, scientists knew a great deal about the makeup of the Earth. From Copper to Protactinium (in chronological order of discovery), by 1920 science had identified 87 of the 118 elements known today, and even had a good approximation of what percentage of each element the Earth was comprised. Astronomers could also observe the heavens and determine what things in space were made of.
Invented in 1876, an instrument called the spectrograph (or spectrometer) dissected light from celestial objects, including planets and stars. This allowed scientist to “see” which chemical elements comprised these distant bodies. The spectrograph did not, however, indicate what percentage of each element there was in a given extraterrestrial object. Prevailing theory at the time stated that, since all the same elements known on Earth were seen in the stars, it must be that the elements in stars were found in the same proportions as on Earth. This theory was wrong, but it was dogma until Cecilia Payne became passionate about astronomy and made a crucial discovery.
Cecilia Helena Payne (1900-1979), was born in Wendover, England. Educational opportunities for girls were extremely limited back then, relative to the opportunities for boys. To meet the education needs of her younger brother, Cecilia’s family moved to London where she attended St. Mary’s College, then switched to St. Paul’s Girls’ School which allowed her to study mathematics, science, and music. Her music teacher was Gustav Holst, the composer who wrote The Planets. Holst pioneered music education for women at St Paul’s Girls’ School. It’s said that he was a superb music teacher, who urged Cecilia to pursue a career in music. She however, was drawn to science. A scholarship allowed her to attend Newnham College, Cambridge University. A lecture she attended, given by Arthur Eddington about his 1919 expedition, changed her life. He had travelled to the coast of Africa to test Einstein’s general theory of relativity by observing and photographing stars at the edge of the solar eclipse in that year. Eddington’s lecture so moved Cecilia that astronomy became her life-long passion.
Upon completing her studies, she received a certificate rather than a degree. Cambridge University only granted degrees to men, not women, until 1948. Realizing that her only career path in the UK was in teaching, she sought a scholarship in the United States to pursue a graduate degree. A fellowship was extended to her to study at Radcliffe College, in the Harvard College Observatory. In 1925, she was the first person, man or woman, to earn a PhD in Astronomy from Radcliffe College, Harvard University.
Her PhD thesis, Stellar Atmospheres; A Contribution to the Observational Study of High Temperature in the Reversing Layers of Stars, contained the breakthrough theory that should have rewarded her with worldwide fame. In short, she had discovered that most elements found in the Sun and other stars were indeed present in Earth-like proportions, except, Hydrogen and Helium were present in massive quantities. This meant that Hydrogen and Helium were far and away the most common elements in the Universe. This fundamental fact opened the door to many other important discoveries in astrophysics.
Cecilia stayed on at Harvard, teaching classes and continuing work in the observatory making important new discoveries, but employed as a “technical assistant” and a teaching assistant. Sexism stood in the way of promotion. She wasn’t given a full professorship until 1956. Later she became Chair of the Department of Astronomy, the first woman to head a department at Harvard. She retired from teaching in 1966.
Cecilia Payne became an American citizen in 1931. She met her future husband, astrophysicist Sergei Gaposchkin in Germany while touring Europe in 1933. They married in 1934 and had three children.
In this video, an enthusiastic and energized Caitlan Hofmeister fills in a few details. “Great Minds of Astronomy: Cecilia Payne-Gaposchkin” (5:35):
Question of the Night: Wish upon a star.