Graziano & Raulin
Research Methods (9th edition)
Claudius Ptolemy (2nd Century A.D.) was an Alexandrian astronomer, mathematician, and geographer.
Ptolemy is best known for his development of a mathematical system of the order and function of the heavenly bodies. In his system the Earth was viewed as the stationary center of the universe, around which orbited the moon, the five then-known planets, and the sun. Surrounding this system were the fixed stars.
Ptolemy’s model was a true scientific theory that had been developed with careful reason and mathematical precision. It was successful in bringing together many astronomical observations into a single unified theoretical model and depicted the complex set of phenomena (planetary motion) as being controlled by a precise and fairly simple law. This geocentric system (i.e., Earth-centered) was the major theory of planetary motion for 1300 years. It was eventually supplanted by the Copernican heliocentric system (sun-centered) in the 16th Century.