As we continue to learn about Henrietta’s research, we see she produced numerous advances in the field. Henrietta discovered a means to not only identify, but rank the magnitudes of stars using photographic plates. Henrietta discovered a way by which astronomers became better able to accurately measure extra galactic distances known as the period-luminosity relation. She also discovered more variable stars than any other astronomer of her time.
Pickering soon promoted Henrietta to department head of the photographic photometry (science of measuring the brightness of stars). In 1912, Henrietta, by comparing different photographs of the same variable star, especially those stars of the “Cepheid” type that had bright-dim cycle periods, established that the slower the blink time the more light or brightness the star contained.
The Cepheid research excited Henrietta, but Pickering hired her to do a specific job, and would not allow her or the other “computers” to veer from their assigned tasks. Cecilia Payne-Gaposchkin, who never knew Leavitt, felt that by not giving Henrietta full rein to explore her passion for variable stars, “condemned a brilliant scientist to uncongenial work, and probably set back the study of variable stars for several decades.”1
“…it ruthlessly relegated Miss Leavitt to the drudgery of fundamental photometry when her real interest lay in the variable stars that she had begun to discover in the Magellanic Clouds.”2
"What a variable-star 'fiend' Miss Leavitt is," wrote Charles Young of Princeton in a letter to Pickering. "One can't keep up with the roll of the new discoveries."3
One of Henrietta’s discoveries concerned the redness of stars. She found that fainter stars were usually redder than brighter ones. This led her to question “whether the light was possibly reddened by interstellar absorption.”4
1George Johnson. Miss Leavitt’s Stars: The Untold Story of the Woman Who Discovered How to Measure the Universe. (New York: W. W. Norton & Co., 2005), 91.
2Cecilia Payne-Gaposchkin. Cecilia Payne-Gaposchkin: an Autobiography and other Recollections. (Great Britain: Cambridge University Press, 1984), 145.
3http://www.encyclopedia.com/topic/Henrietta_Leavitt.aspx (accessed January 20, 2015).
4Harry G. Lang, Bonnie Meath-Lang. Deaf Persons in the Arts and Sciences: A Biographical Dictionary. (Westport, Connecticut: Greenwood Press, 1995), 221.