The Earth: Center of the Universe
The cosmological theory which was universally accepted in Copernicus' time placed the earth in the center of the universe. It was based on the Almagest (The Great Compilation), a book written by Ptolemy in the second century BC. According to this geocentric model of the universe the earth was surrounded by eight spheres which encircled it. For over 12 centuries the model served astronomers, scientists and theologians. The moon, sun, planets and stars each occupied a separate sphere which moved in accordance with the perceived motion of the celestial body occupying it. The model envisioned that the moon occupied the first sphere, Mercury the second, Venus the third, then came the sun, followed by Mars, Jupiter and Saturn. The fixed stars occupied the eighth sphere. Theologians placed heaven on the ninth sphere, and by symmetry, placed nine rings of hell below the surface of the earth.