Harlow Shapley (1885-1972), the US astronomer. The son of a farmer, Shapley entered the University of Missouri with the intention of studying journalism but soon switched to astronomy. In 1915 using Leavitt's 'Cepheid variable' method of estimating stellar distances, Shapley was able to provide the first reasonable picture of the structure and size of our own galaxy. He studied the distribution of globular star clusters by means of the cepheid variables within them, and showed that they are concentrated disproportionately in the direction of Sagittarius. This, he argued, must be the centre of our disc-shaped galaxy.