In 1925, Cecilia Payne-Gaposchkin ran the numbers and discovered that stars — including our sun — are made almost entirely of hydrogen, overturning everything astronomers thought they knew about the cosmos. She was told she was wrong. She changed her own thesis to say so. Then the man who told her to change it claimed the discovery as his own a decade later. This episode is about what the stars are made of, how we actually know, and what it costs science when it silences the people doing the work.