George West Wetherill, a pioneer of geochronolgy and planetary science, passed away from heart failure at his home in Washington, D.C., on 19 July 2006, one month short of his 81st birthday. Wetherill, director emeritus of the Carnegie Institution of Washington's Department of Terrestrial Magnetism, made major contributions to a wide variety of fields, including geochronology and the formation of the planets.