Fred Whipple was an American astronomer known for his significant contributions to the study of comets. He was born on November 13, 1906, and passed away on April 30, 2004. Whipple is best known for developing the "dirty snowball" model of comets, which describes their composition as a mixture of ice and dust. In addition to his work on comets, Whipple served as the director of the Harvard-Smithsonian Center for Astrophysics and was involved in various space missions. His research helped improve our understanding of the solar system and the behavior of celestial bodies, influencing both amateur and professional astronomers.