Dr. Cecilia Payne-Gaposchkin was an astronomer credited with discovering the chemical composition of stars. Born in England, she earned a scholarship to Cambridge University where she studied physics. After graduating, she attended Harvard University to pursue a doctorate in astronomy. In 1925, she presented her thesis on stellar spectra, dubbed as “the most brilliant PhD thesis ever written in astronomy” by Otto Struve. Payne concluded that stars were primarily composed of hydrogen and helium, a revolutionary discovery that changed how astronomers perceive the universe. After receiving her doctorate, she continued to work at Harvard but was denied a promotion to professor because she was a woman. In 1956, she became the first female professor at Harvard and the first woman to become department chair.