Celestial Motion: A Heavenly Romance with the Solar System
Starting with the ancient civilizations’ recognition of the regular movements of the sun and moon, chains of observations bind our conceptions of the heavens. It was comforting to connect cyclic changes in the position of the sun on the horizon with recurring seasons. The regular waxing and waning of the moon provided a convenient time interval for calendar design. With the help of familiar star patterns, called constellations, ancient travellers oriented themselves at night and reckoned passage of hours without the sun. By the regular appearance and disappearance of well-known constellations, they tracked the seasons. The faithful path of the sun through the constellations of the zodiac, a circle of animal-shaped star patterns, provided a reliable, annual calendar visible in the sky.