"This book details the history of one of astronomy's many spurious objects, the satellite of Venus. First spotted in 1645, the non-existing moon was "observed" more than a dozen times until the late eighteenth century. Although few astronomers believed in the existence of such an object after about 1770, it continued to attract attention for at least another century. However, it has largely disappeared from the history of astronomy, and the rich historical sources have never been exploited. The story of the enigmatic satellite in its proper historical context demonstrates that it was much more than a mere curiosity in the annals of astronomy. Frederick II of Prussia was familiar with it, and so were Bonnet, Kant and Voltaire. The painstaking attempts to either prove or disprove its existence led to the development of many new perspectives both practical and philosophical. The satellite of Venus belongs to the same category as other fictitious celestial bodies (such as the planet Vulcan), yet it had its own life and fascinating historical trajectory. By following this trajectory, the history of planetary astronomy is addressed in a novel way."--book jacket.