Henrietta Leavitt was an American astronomer born in 1868. She worked at the Harvard College Observatory, where she studied variable stars, particularly the Cepheid variables. Her groundbreaking research helped establish a relationship between a star's brightness and its pulsation period, which later became crucial for measuring distances in the universe. Leavitt's work laid the foundation for future astronomers, including Edwin Hubble, who used her findings to determine the scale of the universe. Despite facing challenges as a woman in science during her time, her contributions significantly advanced the field of astronomy and our understanding of the cosmos.