Transcript: Over a hundred years ago dozens of women labored in the basement of the Harvard College Observatory paving the way for a modern understanding of stars. These women were paid 25 cents an hour, less than half of what a man would make for similar work, to do the painstaking and tedious work of classifying photographic stellar spectra. Large photographic plates had thousands of individual tiny spectra superimposed on them. The women observed these spectra through a magnifier glass, made notes of the wavelengths of the prominent lines, and calculated the positions and wavelengths of the lines. No computers existed at the time, so these calculations were very tedious. These women were not allowed to be staff members of Harvard College Observatory. They could not take classes, and they could not even earn a degree at Harvard University where they worked. Their work, however, was central to the understanding of stars by classification. Annie Cannon was the most prominent of these stellar classifiers or computers. In her working life she classified over 225 thousand stars, individually and by hand, and she made large and increasing contributions to the subject as she more deeply understood the nature of stellar spectra. The stellar classification scheme that she produced is still in use today.