Celestial spheres
IN ANCIENT COSMOLOGICAL MODELS, ROTATING SPHERES MADE OF AETHER IN WHICH THE STARS OR PLANETS ARE EMBEDDED
Planetary sphere; Heavenly sphere; Sphere (geocentric); Planetary spheres; Orb (astronomy); Celestial orb; Two Sphere Universe; Crystalline celestial spheres; Celestial Spheres; Sphere of spheres; Turning spheres; Heavenly spheres
The celestial spheres, or celestial orbs, were the fundamental entities of the cosmological models developed by Plato, Eudoxus, Aristotle, Ptolemy, Copernicus, and others. In these celestial models, the apparent motions of the fixed stars and planets are accounted for by treating them as embedded in rotating spheres made of an aetherial, transparent fifth element (quintessence), like jewels set in orbs.