William Sheehan retired after 30 years in practice as a psychiatrist, earned his MD degree (1987) and completed his psychiatric residency (1992) from the University of Minnesota Medical School. He has been a lifelong amateur astronomer and a historian and author of books on astronomy and history of astronomy including: Planets & Perception (Tucson, 1988), Worlds in the Sky (Tucson, 1992), The Immortal Fire Within: the life and work of Edward Emerson Barnard (Cambridge, UK, 1995), The Planet Mars (Tucson, 1996), In Search of Planet Vulcan (with Richard Baum) (New York, 1997),  Epic Moon (with Thomas A. Dobbins) (Richmond, VA, 2001), Mars: the lure of the red planet (with Stephen James O'Meara (Amherst, NY, 2001), Transits of Venus (with John Westfall) (New York, 2004), Galactic Encounters (with Christopher Conselice) (Springer, 2015), Celestial Shadows: eclipses, transits and occultations (with John Westfall, 2015), Camille Flammarion's Planet Mars (with Sir Patrick Moore) (Springer 2015), Discovering Pluto: exploration at the edge of the Solar System (with Dale P. Cruikshank) (Tucson, 2018), Neptune: from Grand Discovery to a World Revealed (Springer, 2021), Discovering Mars (with Jim Bell) (Tucson, 2021). He has also written Mercury, Venus (with Sanjay Limaye), Jupiter (with Thomas A. Hockey), and Saturn for Reaktion Books' Kosmos Series. He is a long-time contributing editor for Sky & Telescope, a frequent contributor to Astronomy, the Journal for Astronomical History and Heritage, Scientific American and other journals, and a prolific contributor of essays to the Biographical Encyclopedia of Astronomers.  He is also a fellow of the John Simon Guggenheim Memorial Foundation (2001), and a recipient of the Gold Medal of the Oriental AstronomicalAssociation (2004).  He is a past member of the IAU's Working Group on Planetary System Nomenclature, and asteroid Sheehan (16037) has been named in his honor.