Cecilia Payne-Gaposchkin: March 19

Cecilia Payne-Gaposchkin discovered that hydrogen and helium were the overwhelming constituent of the stars. When her dissertation was reviewed, astronomer Henry Norris Russell dissuaded her from concluding that the composition of the Sun is different from that of the Earth, contradicting the accepted wisdom at the time. However, he changed his mind four years later after deriving the same result by different means. After Payne was proven correct, Russell was often given the credit, although he himself acknowledged her work in his paper.