Geocentric system

Geocentric System
Related Category: Astronomy: General
see Ptolemaic system.
More on Geocentric System
Ptolemaic System - historically the most influential of the geocentric cosmological theories, i.e.

Geocentric system (Ptolemy) counted the Moon and Sun as planets, along with Mercury, Venus, Mars, Jupiter, and Saturn
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1550 ...

The geocentric system of Tycho Brahe (1546-1601) shows the Moon and the Sun revolving around Earth while Mercury, Venus, Mars, Jupiter, and Saturn revolve around the Sun, all surrounded by a sphere of fixed stars.

(See Ptolemy's theory of the solar system.) In the first book of the Almagest, Ptolemy describes his geocentric system and gives various arguments to prove that, in its position at the center of the universe, the Earth must be immovable.

In 1543 the geocentric system met its first serious challenge with the publication of Copernicus's De revolutionibus orbium coelestium, which posited that the Earth and the other planets instead revolved around the Sun.

Part of the purpose of Somnium was to describe what practicing astronomy would be like from the perspective of another planet, to show the feasibility of a non-geocentric system.

The heliocentric model was able to easily explain things that the geocentric system had a hard time doing, most notably the seemingly retrograde motion of the planets.

Heliocentrism is the idea that the sun is the center of the universe; it is opposed to the Ptolemaic system and other geocentric systems, according to which Earth is at the center of the universe.

For example, Hipparchus (Greek ~3 century BC) discovered the precession of the equinoxes, (Greek in Alexandria ~100 AD) systematized the geocentric system of planets, (Polish, 1500s) proposed the heliocentric system, ...

This theory was rejected by most Greek philosophers, who regarded the heavy earth as a motionless globe around which the light, incorporeal bodies revolve. This theory, the geocentric system, remained virtually unchallenged for about 2000 years.

See also: Geocentric, Earth, Planet, Universe, Time