Cecilia Payne-GaposchkinMay 10, 1900 – (1979-12-07)December 7, 1979) was a British-born American astronomer and astrophysicist. Her work on the cosmic makeup of the universe and the nature of variable stars was foundational to modern astrophysics.
She determined that stars were composed primarily of hydrogen and helium in her 1925 doctoral thesis. Her groundbreaking conclusion was initially rejected by leading astrophysicists, including Henry Norris Russell, because it contradicted the science of the time, which held that no significant elemental differences distinguished the Sun and Earth. Independent observations eventually proved that she was correct.
Despite completing her studies, because she was a woman Payne was not eligible to receive a degree from the University of Cambridge. Similarly in America, she was not eligible to receive a doctoral degree (PhD) for her studies at Harvard University, as they did not grant doctoral degrees to women at the time. Instead, she received her doctoral degree from Radcliffe College – a liberal arts college for women that began as a study program for women within Harvard.