(Celestial motion; Credit: Hiroyoshi Wada)
(Ptolemaic astronomic model; Credit: Peter Apian, Cosmographia)
(Heliocentric model; Credit: De revolutionibus orbium coelestium)
(Planetary retrograde motion; Credit: EarthSky)
— Revolutions
— The conception of universe shared by many civilizations: sphere, the “perfect shape”
–Conceptual Schemes of Ptolemy (geocentric) & Copernicus (heliocentric)
–Two Sphere Universe (geocentric model)
— northern semisphere spins counterclockwise, southern semisphere spins clockwise
— some stars (polaris & nearby) do not go under the horizon, while others do
— sun’s position moves with the rest of the sky throughout the year
— planetary retrograde motion, not completely explainable with geocentric perspective