Forest Ray Moulton (April 29, 1872 December 7, 1952) was an American astronomer. He was born in Le Roy, Michigan, and was educated at Albion College. After graduating in 1894 (A.B.), he performed his graduate studies at the University of Chicago and gained a Ph.D. in 1899. At the University of Chicago he was associate in astronomy (1898 1900), instructor (1900 03), assistant professor (1903 08), associate professor (1908 12), and professor after 1912. He is noted for being a proponent, along with Thomas Chamberlin, of the Chamberlin-Moulton planetesimal hypothesis that the planets coalesced from smaller bodies they termed planetesimals. Their hypothesis called for the close passage of another star to trigger this condensation, a concept that has since fallen out of favor