Williamina Fleming lived from 15 May 1857 to 21 May 1911. She rose from unlikely and humble beginnings to become an important astronomer whose star classification system formed the basis of all subsequent systems. The wider picture in Scotland at the time is set out in our Historical Timeline.
Williamina Stevens was born in Dundee and attended local schools until the age of 14, when she became a pupil-teacher. In 1877 at the age of 20, she married James Orr Fleming, and the couple emigrated to the Boston, Massachusetts, the following year. Her husband abandoned her when she fell pregnant with their son, Edward, and in order to support herself and her baby she took up a post as maid to Professor Edward Charles Pickering, who worked at the Harvard College Observatory.
Williamina clearly impressed Professor Pickering, who from 1881 employed her to undertake clerical work at the Observatory. In 1886 the Observatory was funded to undertake a new area of work photographing and cataloguing stars. The result was a vast data processing and organisational job. This was undertaken largely by Williamina, who had been placed in charge of a large number of women employed to undertake the repetitive calculations involved. Williamina's major contribution was to devise a system of classifying stars based on their spectra. Her classification system has since been improved and developed, but the system in use today can be traced back to Williamina's work.
In four years she catalogued many tens of thousands of stars and discovered a number of unusual objects, including the Horsehead Nebula. In 1899 Williamina was appointed Curator of Astronomical Photographs at Harvard, and in 1906, she was made an honorary member of the Royal Astronomical Society of London, the first American woman to receive the honour. In 1907 Williamina published an account of over 200 variable stars she had discovered and was subsequently appointed to be honorary fellow in astronomy at Wellesley College. In all she discovered 59 gaseous nebulae, 310 variable stars, and 10 supernovae. Williamina Fleming died of pneumonia in Boston in 1911.