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The basic elements of Ptolemaic astronomy, showing a planet on an epicycle (smaller dashed circle), a deferent (larger dashed circle), the eccentric (×) and an equant (•). Equant (or punctum aequans) is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of the planets. The equant is ...
In Greek antiquity the ideas of celestial spheres and rings first appeared in the cosmology of Anaximander in the early 6th century BC. [7] In his cosmology both the Sun and Moon are circular open vents in tubular rings of fire enclosed in tubes of condensed air; these rings constitute the rims of rotating chariot-like wheels pivoting on the Earth at their centre.
[14]: 62 Ptolemy's work on astronomy was driven to some extent by the desire, like all astrologers of the time, to easily calculate the planetary movements. [ 15 ] : 40 Early Western astrology operated under the Ancient Greek concepts of the Macrocosm and microcosm , and thus medical astrology related what happened to the planets and other ...
Ptolemy did not predict the relative sizes of the planetary deferents in the Almagest. All of his calculations were done with respect to a normalized deferent, considering a single case at a time. This is not to say that he believed the planets were all equidistant, but he had no basis on which to measure distances, except for the Moon.
In classical, medieval, and Renaissance astronomy, the Primum Mobile (Latin: "first movable") was the outermost moving sphere in the geocentric model of the universe. [ 1 ] The concept was introduced by Ptolemy to account for the apparent daily motion of the heavens around the Earth, producing the east-to-west rising and setting of the sun and ...
Ptolemy did not invent or work out this order, which aligns with the ancient Seven Heavens religious cosmology common to the major Eurasian religious traditions. It also follows the decreasing orbital periods of the Moon, Sun, planets and stars.
Depending on the historian's viewpoint, the acme or corruption [citation needed] [dubious – discuss] of Classical physical astronomy is seen with Ptolemy, a Greco-Roman astronomer from Alexandria of Egypt, who wrote the classic comprehensive presentation of geocentric astronomy, the Megale Syntaxis (Great Synthesis), better known by its ...
The Ptolemaic system of celestial motion as depicted in the Harmonia Macrocosmica (1661). Science in classical antiquity encompasses inquiries into the workings of the world or universe aimed at both practical goals (e.g., establishing a reliable calendar or determining how to cure a variety of illnesses) as well as more abstract investigations belonging to natural philosophy.