Cecilia Payne-Gaposchkin, the first woman to earn a PhD in astronomy at Harvard and the first female professor in the university's Faculty of Arts and Sciences, has been commemorated with an English Heritage blue plaque at her home in Notting Hill. Her 1925 thesis suggested that stars are composed primarily of hydrogen and helium, a discovery that fundamentally changed scientific understanding of the universe. She also published hundreds of scientific papers and became a full professor at Harvard.