In 1925, Cecilia Payne wrote a doctoral thesis that correctly identified what stars are made of — and was immediately told she was wrong by the most powerful astronomer in the world. She changed her conclusion to match his, he republished the finding four years later as his own, and for decades the textbooks agreed with him. This is the story of how one equation rewrote the entire chemical recipe of the universe, and why the person who found it had to wait half a century for anyone to say her name.