Philip Shaefer Riggs was born in Chicago on 30 May 1906 and graduated in 1927 from the Carnegie Institute of Technology (Carnegie-Mellon) in physics, eventually obtaining a PhD in astronomy from Berkeley in 1944. He held a series of teaching posts starting at Washburn College, Topeka, Kansas, where he joined the faculty as assistant professor of astronomy in 1937. He left Washburn for an instructorship in astronomy at the University of Illinois in 1938, but returned to Washburn as professor of physics and astronomy in 1939, a post he held until 1947 when he moved to Drake University as an associate professor of astronomy. He was known as an inspiring teacher and popular lecturer at the Drake Municipal Observatory at Waveland Park, rising eventually to become professor and head of the Department of Astronomy, following Daniel Morehouse in that post. He retired in 1976 holding emeritus status at Drake until his death at age 87 from cancer.
Riggs joined the American Astronomical Society in 1937 and was a member of the Federation of American Scientists. He was married in 1939 and had two sons. In 1957 and 1958 he held an NSF Science Faculty Fellowship at Berkeley, and professed special interests in stellar and galactic astronomy. Compiled from a local newspaper account supplied by one of his sons, Norman Riggs, and from an entry in the 14th Edition of American Men and Women of Science.