Stellar movements and working hypotheses: A.S. Eddington’s early astronomical career

Arthur Stanley Eddington (1882–1944) was one of the leading astrophysicists of the first half of the 20th century. He is remembered today chiefly for his research into stellar structure and general relativity, both of which he began to explore in the mid-1910s. He was also a key participant in the famous eclipse expeditions of 1919 that tested Einstein’s theory of gravity. Rather than consider these topics, in this paper I will instead examine Eddington’s early astronomical career, that is, from 1906 to about 1915. In this period, he became a well-trained practical astronomer. Eddington also established himself as a brilliant theoretical astronomer, and in so doing helped to create the role of theoretical astrophysicist through his research into star streaming. He was also, unusually for astronomers of this period, an enthusiastic advocate of the use of “working hypotheses” as crucial tools in astronomical practice. The study of Eddington’s early career therefore has much to tell us about the nature of astronomy in the years around 1910 and about Eddington. The paper underlines, for example, the continuing relevance of the “Greenwich-Cambridge Axis” for the power structure of British astronomy, and the importance of the so-called Sidereal Problem for astronomers at this time even though today it is largely forgotten.