Frontispiece from Johannes Hevelius' Cometographia (Danzig, 1668). Three allegorical figures showing the Aristotelian idea that comets are sublunar (left), the Keplerian notion that comets move on straight line paths (right) and the idea of Johannes Hevelius (center) that comets originate in the atmospheres of Jupiter and Saturn and move about the Sun on a curved trajectory.

Caption taken verbatim from Don Yeomans' Book on Comets (Yeomans, Donald K. 1991. Comets: A Chronological History of Observations, Science, Myth, and Folklore. Wiley Science Editions, New York.)

(Photo from the collection of Don Yeomans.)