Harlow Shapley

From 1941 he was on the original standing committee of the Foundation for the Study of Cycles. Sources
Nature - Obituary. Among these was Source Book in Astronomy (New York: McGraw-Hill 1929—co-written with Helen E.

He is notable for his groundbreaking 1918 work using Cepheid variables to estimate the size of the Milky Way Galaxy and the sun's position within it as well as in 1953 proposing the "Liquid Water Belt" theory now known as the concept of a habitable zone.