De revolutionibus orbium coelestium divided into six "books" (sections or parts), following closely the layout of Ptolemy's "Almagest" which it updated and replaced: Copernicus argued that the universe comprised eight spheres. The outermost consisted of motionless, fixed stars, with the Sun motionless at the center. The known planets revolved about the Sun, each in its own sphere, in the order: Mercury, Venus, Earth, Mars, Jupiter, Saturn. The Moon, however, revolved in its sphere around the Earth. What appeared to be the daily revolution of the Sun and fixed stars around the Earth was actually the Earth's daily rotation on its own axis. Copernicus adhered
The Sun in culture The Sun in culture The Sun, as the source of energy and light for life on earth has been a central object in culture and religion since prehistory. Ritual solar worship has given rise to solar deities in theistic traditions throughout the world, and solar symbolism is ubiquitous. Apart from its immediate connection to light and warmth, the sun is also important in timekeeping as the main indicator of the day and the year. The earliest understanding of the Sun was that of a disk in the sky, whose presence above the horizon creates day and whose absence causes night.