Star and Solar System Maps: A History of Celestial Cartography

Since antiquity, people have observed the night sky in an effort to predict celestial events, help with navigation, coordinate planting activities, and understand their place in the universe. Many cultures viewed the stars as forming fixed heavenly patterns called constellations that reflected issues important to them. The ancient Greeks visualized constellations as allegorical representations of classical heroes, heroines, and monsters from Greek mythology. In contrast, the Chinese saw them as reflections of people and activities on Earth, from the imperial Emperor and his retinue to tradesmen and farm animals. Complicating the fixed order of the heavens were the wandering planets and unexpected events, such as comets and novae. To establish order and predictability, people made maps of the heavens. The mathematical Greeks went so far as to place the stars in a scientific coordinate system that was based on celestial latitude and longitude (today’s declination and right ascension). In time, two kinds of maps emerged: star maps, focusing on stellar placement and constellations, and solar system maps, focusing on planetary locations and, with the advent of the telescope, surface characteristics. But for many centuries, solar system maps were in actuality cosmological diagrams with nested planetary circles centered first on the Earth, then on the Sun, and then expanding into deep space as nebulae and galaxies became identified. Star and solar system maps formed the backbone of stunningly beautiful sky atlases of the 17th to the 19th Centuries. But telescopic and scientific needs called for increased accuracy in star placement using more detailed and enlarged coordinate systems. Constellation images became redundant, and they have largely disappeared in the finely drawn and computer-generated star maps used today. In addition, ever larger telescopes and space probes have allowed us to view the planets and their satellites with stunning accuracy. In this presentation, the history and development of celestial cartography will be discussed using striking images from antiquarian and modern sources.