A woman who came to astronomy in her forties brought order to the names on the Moon

At the time the Moon spoke several languages at once. The makers of the main lunar maps, Beer and Mädler, Schmidt, Neison, gave one and the same feature different names. Sometimes it went the other way, and one name landed on different features. An international committee took on the mess. One of its members, Samuel Saunder, asked Blagg to help, and she collated every map. Saunder died in 1912; in 1913 her Collated List of Lunar Formations came out, with nearly five thousand names.

During the First World War she cared for refugee children from Belgium. In January 1916 she became one of the first five women elected to the Royal Astronomical Society. When the International Astronomical Union was founded, she was invited onto its lunar commission. In 1935 she and the Czech amateur astronomer Karl Müller published the two-volume Named Lunar Formations. As David Portree writes on the LROC website, it remained the definitive guide to lunar names at least until the Moon missions.

For her last eight years she had heart trouble, yet she was still solving the chess problems in a Sunday paper a few weeks before she died in 1944. The crater named after her is a small one. But every name on the great lunar maps once passed through her hands.