The second half of the nineteenth century was a period of extraordinary scientific progress. In astronomy, bigger and better telescopes, and the techniques of spectroscopy and photography, brought about a revolution in humankind's vision of the universe. The documentation – in the English-speaking world at least – of the astronomical labours of that important era was almost entirely due to Agnes Mary Clerke, historian of astronomy and painstaking chronicler of astrophysical discovery as she witnessed it over thirty years of her active life. This remarkable woman, educated solely within her own family and through her own private studies, not only kept abreast of astronomical progress world-wide but also had a genuine understanding of the matters on which she reported and the gift of communicating them through her fluent and prolific writings. Her books – in particular her Popular History of Astronomy during the Nineteenth Century, first published in 1885 and reprinted over almost twenty years – are treasured by historians and by amateur lovers of astronomy alike as sources of reliable and enjoyable information on that period. She was also much in demand in her lifetime as a contributor to literary journals and encyclopaedias.

Agnes Clerke numbered among her circle of friends and correspondents many of the eminent astronomers of the day. Unobtrusive and gentle by nature, she nevertheless became an authority on astrophysics and a figure of respect in the literary world.