(Edward) Walter Maunder (April 12, 1851 – March 21,1928) was an English astronomer.
Munder is remembered for his study of sunspots and the solar magnetic cycle that led to his identification of the period from 1645 to 1715 that is now known as the Maunder Minimum.
Part of Maunder’s job at the Observatory involved photographing and measuring sunspots, and in doing so he observed that the solar latitudes at which sunspots occur varies in a regular way over the course of the 11 year cycle. After 1891, he was assisted in his work by his second wife, Annie Scott Dill Maunder (née Russell), a mathematician educated at Girton College in Cambridge. She worked as a “lady computer” at the Observatory from 1890 to 1895. In 1904, he published their results in the form of the “butterfly” diagram.
After studying the work of Gustav Spörer, who examined old records from the different observatories archives looking for changes of the heliographic latitude of sunspots, Maunder announced Spörer’s conclusions in own paper edited in 1894. The period, recognised earlier by Spörer, now bears Maunder’s name.
He travelled extensively for observations going to places such as the West Indies, Lapland, India, Algiers, Mauritius. His last eclipse expedition was to Labrador for the Solar eclipse of 30 August 1905 at the invitation of the Canadian government.