William B. McKinnon, Professor of Earth, Environmental, and Planetary Sciences at Washington University in St. Louis, was installed as the Clark Way Harrison Distinguished Professor in a ceremony on September 30, 2025. He is currently serving as interim director of the McDonnell Center for the Space Sciences, where he is a longtime fellow.
McKinnon began his formal studies of the solar system at Massachusetts Institute of Technology, where he studied physics and geology while earning a bachelor’s degree in earth and planetary sciences. After earning his master’s degree in planetary science and doctorate in geophysics and planetary science from the California Institute of Technology, McKinnon was a postdoctoral associate at the Lunar and Planetary Laboratory of the University of Arizona in Tucson.
McKinnon’s deep childhood interest in the planets led to his doctoral research, which was valorized by the astonishing revelations from NASA’s Voyager mission encounters with Jupiter and its moons. After post-doctoral research with a member of the Voyager imaging team, there was no turning back. The Voyagers would ultimately pass each giant planet, offering a rich set of data on icy satellite geology to compare and contrast with that of the rocky planets. McKinnon was also active in an effort to push such exploration farther. This culminated in the launch and success of NASA’s New Horizons mission to Pluto and the Kuiper Belt, a region of icy space objects beyond Neptune’s orbit. Closer in, exploration of Jupiter’s satellites remained frustratingly incomplete, which has led to the launch of NASA’s Europa Clipper, which will explore Jupiter’s potentially habitable ocean moon, and the European Space Agency’s Jupiter Icy Moons Explorer, which will focus on Ganymede. McKinnon has mission roles in both projects.
Professor McKinnon has served as chair of the Division for Planetary Sciences (DPS) of the American Astronomical Society, president of the Planetary Sciences section of the American Geophysical Union (AGU), and chair of the Outer Planets Assessment Group for NASA. He has served on numerous National Academies committees, including the most recent Decadal Survey for Planetary Sciences and Astrobiology. He has been a journal editor, as well as a visiting scientist at MIT, NASA’s Jet Propulsion Laboratory, and Southwest Research Institute. McKinnon has been honored with the Kuiper Prize of the DPS for outstanding lifetime achievement in the field of planetary science and the Gilbert Award of the Planetary Geology Division of the Geological Society of America (GSA) for outstanding contributions to the solution of fundamental problems in planetary geology. He is a fellow of the GSA, AGU, and American Association for the Advancement of Science and an elected member of the National Academy of Sciences. A space rock, asteroid 9526 Billmckinnon, is named for him.
McKinnon joined WashU’s Department of Earth and Planetary Science (now Earth, Environmental, and Planetary Sciences) in 1982. He resides in Kirkwood and has three adult children, Brianna, Liam, and Evan. He enjoys travel, music, cooking, and all the many cultural activities available in Saint Louis with his family and friends.
The Clark Way Harrison Distinguished Professorship was established in 1991 through Miss Maxine Harrison’s bequest commitment. As determined in her will, this was initially an endowed visiting professorship in honor of her father, created to benefit the Arts & Sciences disciplines of biology, chemistry, Earth and planetary science, philosophy, physics, and future studies concerned with the brain, mind, or neurosciences. She had a strong preference for using her funds to bring world-class scholars to WashU for flexible periods, thereby enhancing the student experience.
Miss Harrison was born in January 1902. She graduated from Smith College in 1924 and started working for Parke-Bernet Galleries in 1940, writing painting catalogues. In 1948, she went on to work as an international correspondent for newspapers in Mexico and the Philippines. Maxine was accredited to the White House press for Eisenhower and Kennedy presidential trips. She passed away in October 1991, at the age of 89, and her last residence was in Locust Valley, New York. She was the only daughter of Alle Davis Harrison, who passed away in 1940, and Clark Way Harrison.
Mr. Harrison was born in Glasgow, Missouri, and graduated from WashU. In 1899, he became foreign sales manager of the United States Cast Iron Pipe and Foundry Company, with headquarters in London. In 1911, Mr. Harrison returned to the United States as treasurer and manager of Bloomingdale Rubber Company, and he was elected president in 1919. He had also been president of the Rubber Reclaimers Association. A resident of Rose Valley, Pennsylvania, he passed away in September 1958 at the age of 90
