Cecilia Payne-Gaposchkin

Cecilia Payne was born in Britain in 1900 and studied at Cambridge, where she completed her work but couldn't receive a degree because she was a woman. She moved to America and pursued astronomy at Harvard, which also wouldn't grant her a PhD, so Radcliffe College awarded her doctoral degree in 1925 for a thesis that upended cosmology: stars were made primarily of hydrogen and helium, not the same mix of elements as Earth. Henry Norris Russell and others rejected the conclusion outright until independent data forced them to admit she'd been correct. She kept working, publishing major texts on stellar luminosity and variable stars through the 1930s and 1950s, and in 1956 became the first woman appointed professor and department chair at Harvard. She died in December 1979, having spent a career clearing a path that hadn't existed when she started.