Do we really know what we see through a telescope? How does the ocular system construct planetary images, and how does the brain interpret them? Drawing on both astronomical and psychological data, William Sheehan now offers the first systematic analysis of the perceptual and cognitive factors that go into the initial structuring of a planetary image and its subsequent elaboration. Sheehan details the development of lunar and planetary astronomy beginning with Galileo's study of the moon, and focuses particularly on the discover of "canals" on Mars. Through each episode he underscores a perceptual or psychological theme, such as the importance of differences in vision, tachistoscopic perceptual effects, the influence of expectation and suggestion on what one sees, and the social psychology of scientific discovery. Planets and Perception is a provocative book that will intrigue anyone who has ever looked through a telescope. In addition, it offers the psychologically-oriented reader a case history in the processes of perception unlike any other in the literature.

William Sheehan is a psychiatrist, writer, and amateur astronomer.

"Incisive, convincing, even entertaining, it is a landmark volume that reveals, explains, and puts into perspective one of the most exciting chapters in the history of visual planetary astronomy."—Journal of the British Astronomical Association"

Planets and Perception will interest most anyone who has ever looked through a telescope and offers the psychology oriented reader a unique case history in the processes of perception."—Earth Science

"We need to learn what it was about Galileo, Cassini or Herschel that made them right. But before we can find the answer to that question, we need to know how Schiaparelli and many of his contemporaries could be so wrong. Sheehan's account goes a long way toward answering that question." —Nature

"This is a well-accomplished and thought-provoking work. . . . An important and accessible contribution."—The Observatory

"A great read on the early history of telescopes in the pursuit of planetary information."—Explorers Journal