In the early 20th century physicists reading the spectrum lines from the sun thought that the sun was made mostly of iron which made sense because iron is the ultimate output from the reactions occurring in the sun. However one young student named Cecilia Payne read the spectrum differently and hypothesized that the spectrum really showed that the sun was mostly hydrogen. Because she was a woman she was completely shut down by the male establishment and even after she was proven to be right she never received the proper recognition for her findings.

(Book – E=mc2: a biography of the worlds most famous equation : David Bodanis)