called "aether". The heliocentric model that replaced it involved the radical displacement of the Earth to an orbit around the Sun; sharing a placement with the other planets implied a universe of heavenly components made from the same changeable substances as the Earth. Heavenly motions no longer needed to be governed by a theoretical perfection, confined to circular orbits.

Copernicus' 1543 work on the heliocentric model of the Solar System tried to demonstrate that the Sun was the center of the