Whipple, Fred Lawrence, 1906-2004, American astronomer, b. Red Oak, Iowa. After graduating from the Univ. of California, Berkeley (Ph.D. 1931), he accepted a position at Harvard, where he remained for the rest of his career. During World War II he helped develop the aluminum chaff that was used to confuse enemy radar, but he is best known for proposing in a 1950 paper that comets were frozen gases with other substances mixed in, not unlike a "dirty snowball." Whipple, who headed the Smithsonian Astrophysical Observatory from 1955 to 1973, also anticipated artificial satellites, establishing an early tracking station before the first Sputnik launch (1957).