Today in the history of astronomy, a groundbreaking stellar astronomer is born.

| Published: May 10, 2026

Cecilia Payne-Gaposchkin sits at her desk at Harvard University; in 1956, she was named chair of the astronomy department there. Credit: Smithsonian Institution/Science Service/restored by Adam Cuerden - Air and Space Museum online gallery (public domain)

Born May 10, 1900, Cecilia Payne-Gaposchkin was also the first person to discover that stars are primarily made up of hydrogen and helium — a finding that took years to be acknowledged by the scientific community.

Born in Wendover, England, Payne-Gaposchkin was an active student. She attended Cambridge University with an interest in science but was unsure of what to focus on. There, she met astronomer Arthur Eddington , who — after she bombarded him with an onslaught of questions — gave her access to professional astronomical journals.…