English Astronomy Pioneer Mary Adela Blagg (1858–1944)

Blagg Crater
Blagg Crater located on the Sinus Medii

A century ago, having a conversation about the various features on the Moon could prove a difficult task as the maps of its surface were not standardized. In fact, it was left up to whoever made a particular lunar map to come up with a title for its craters and other features, and so a confusing situation then arose in which a single crater could go by four or five different titles, depending on the opinions and preferences of a particular lunar cartographer.

This situation might have continued that way for decades longer if it hadn’t been for the efforts of a female English astronomer named Mary Adela Blagg, whose tireless work in the field of selenography helped provide a standard set of names for the surface and physical features on the Moon.

Born in 1858, Blagg went to school in London, and despite never attending college, she was able to become adept at advanced mathematics by studying her brother’s textbooks. It wasn’t until around 1904, however when she was in her late 40s, that astronomy became a consuming interest of hers after enrolling in a university extension course and attending a lecture series given by Joseph Hardcastle, grandson of the celebrated astronomer William Herschel who in 1781 discovered Uranus.

Such was Mary Adela Blagg’s talent and passion for the subject that her tutor suggested that she should turn her attention towards the field of lunar nomenclature, and more specifically on the problem of developing a uniform system for naming the Moon’s surface and formations. In 1905, the International Association of Academies subsequently tasked Blagg with collecting the various names of the Moon’s features, and following eight years of research, and guidance from astronomers Joseph Hardcastle and H.H. Turner, she eventually published her book entitled Collated List of Lunar Formations (1913), complete with an index of 4,789 entries.

In her first book, she pieced together the numerous mismatched names of various features on the Moon sourced from other maps, and proposed new standard names for them. In addition, she used early telescopes and photographs taken of the Moon to pin down the exact locations of the features. However, while Mary Blagg’s story is known by some, there is a big misconception that she worked under the supervision of someone else. We now know that her work was mostly independent, and that although she received input from the notable astronomers with whom she exchanged letters, Blagg performed the calculations herself.

Furthermore, she did so while also finding time to work on another field of study involving variable stars, and making breakthroughs in measuring their brightness, something that was rather complex before the advent of computers. Her work subsequently served as a foundation for the work of future astronomers, with one example being her observation that the star Beta Lyrae’s cycle of brightening and dimming had grown slower, thus laying the foundation for later astronomer to use her work to discover that the star is in fact part of a binary system that is slowly being devoured by its companion star.

Even her contemporaries realized the impact Blagg was having on the field of astronomy, and in 1920 the International Astronomical Union appointed her to its Lunar Commission where she was free to carry on her standardization project, together with Viennese amateur astronomer Karl Müller. In 1935, Blagg and Müller then published their work called Named Lunar Formations, which was used as a standard reference on lunar nomenclature until it was supplanted by System of Lunar Craters, whose catalogs were released between 1963-1966.

Blagg passed away in 1944, but her work still lives on. Not only did she contribute greatly to furthering modern astronomy, but she also broke through the glass ceiling in the field, relaxing standards that had kept women from being taken seriously as scientists, and opening the doors for women to have a place at NASA. Mary Adela Blagg has since been honored with having a crater on the Moon named after her, which is located on the small lunar mare called Sinus Medii (photo).

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