By middle age, she became interested in astronomy after attending a university extension course taught by Joseph Hardcastle, John Herschel's grandson.

In 1907, she was appointed by the newly formed International Association of Academies to build a collated list of all of the lunar features.

These were published in a series of ten articles in the Monthly Notices, in which Turner acknowledged that a large majority of the work had been performed by Blagg.

[4] After the publication of several research papers for the Royal Astronomical Society, she was elected as a fellow in January 1916,[5] after being nominated by Professor Turner.

However, her paper was forgotten until 1953,[8] when it was found that her predictions had been validated by discoveries of new planetary satellites unknown at the time of publication.

During her life, Blagg performed volunteer work, including caring for Belgian refugee children during World War I.