Much of post 1920s astronomy rests on her shoulders. Without her, we wouldn’t have a three-dimensional sky. Leavitt’s Law allowed us to measure distances in other galaxies as early as 1912. But how many people have ever heard of Henrietta Leavitt? We wanted to know about this ‘hidden woman’ of astronomy, so in this episode of the Big Questions podcast we ask Dr Becky Smethurst from the University of Oxford’s Department of Physics “Who was Henrietta Leavitt?”.