Cecilia Payne

Cecilia Payne-Gaposchkin (born Cecilia Helena Payne; (1900-05-10)May 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 Russe