Final answer:
Cecilia Payne-Gaposchkin is credited with the seminal discovery of the composition of the Sun and stars in her 1925 doctoral thesis, despite facing gender discrimination in her academic career.
Step-by-step explanation:
Cecilia Payne-Gaposchkin, an esteemed astronomer and astrophysicist, is celebrated for her groundbreaking 1925 doctoral thesis, which supposedly led to the discovery of what the Sun and stars are made of. Despite her significant contributions to the field, she faced substantial gender biases, which delayed her formal recognition at Harvard University where she worked. It wasn't until 1938 that she received a formal appointment, and only in 1956 was she appointed a professor.