Ptolemaic System
Related Category: Astronomy: General
(tl´´m´k), historically the most influential of the geocentric cosmological theories, i.e.
Ptolemaic system
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PTOLEMAIC SYSTEM
, in astronomy, theory of the order and action of the heavenly bodies, advanced in the 2d century ad by the Greek astronomer Ptolemy.
The Ptolemaic system
In the Ptolemaic system, each planet is moved by two or more spheres: one sphere is its deferent which is centered on the Earth, and the other sphere is the epicycle which is embedded in the deferent.
PTOLEMAIC SYSTEM
The Ptolemaic System is an outdated view of the solar system written about by Ptolemy (about 87-150) in his major work, Almagest (Mathematical Syntaxis).
The Ptolemaic system was, in a geometrical sense, defensible; it harmonized fairly well with appearances, and physical reasonings had not then been extended to the heavens.
In the Ptolemaic system, deferents were large circles centered on the Earth, and epicycles were small circles whose centers moved around the circumferences of the deferents.
Equant - In the Ptolemaic system, the point from which the motion of the epicycle around the deferent is uniform ...
Nasir al-Din al-Tusi (b. 1201) resolved significant problems in the Ptolemaic system by developing the Tusi-couple as an alternative to the physically problematic equant introduced by Ptolemy.
After centuries of developments by Babylonian and Greek astronomers, western astronomy lay dormant for fourteen centuries until Nicolaus Copernicus modified the Ptolemaic system by placing the sun at the center of the universe.
Another failing of the Ptolemaic system, which Copernicus corrected in his heliocentric model, was the problem of precession. This characteristic of the Earth's movement is apparent only with observation over long periods of time.
Epicycles are circular orbits within orbits that were used to (incorrectly) describe the orbits of objects in the Ptolemaic system (about A.D. 150).
8 The Copernican model of the solar system explains the varying brightnesses of the planets, something the Ptolemaic system largely ignored.
This system became known as the Ptolemaic system and predicted the positions of the planets accurately enough for naked-eye observations (although it made some ridiculous predictions, ...
This famous phrase is usually taken to mean the resorting to desperate expedients to "save" or rescue the Ptolemaic system. But it meant no such thing.
In contrast, scientists before Copernicus ascribed to the Ptolemaic system, also known as the geocentric theory. The Ptolemaic system stated that all the planets, the Moon, and the Sun orbited the Earth, which was the center of the universe.
In particular, the geocentric Ptolemaic system was the accepted theory to explain the motion of the heavens until Nicolaus Copernicus, and subsequently Johannes Kepler and Galileo Galilei proposed a heliocentric system in the 16th century.
Thus, as the following diagrams indicate, in the Ptolemaic system Venus should always be in crescent phase as viewed from the Earth because as it moves around its epicycle it can never be far from the direction of the sun (which lies beyond it), ...
Many diagrams of the Ptolemaic system to be found on the WWW get this wrong, but Figure 2.19 of Zeilik and Gaustad (2nd edition) gets it right.
spread throughout the West, the Ptolemaic system became very widely accepted, and although the Church never issued any formal pronouncement on the question of alien life, at least tacitly, the idea was aberrant.
But the observational evidence of the time favoured the epicycle-based Ptolemaic system.
However, even with this reasoning, there were stronger reasons to believe in a heliocentric model. But, this thinking was lost, and the preponderance of the Ptolemaic system pervaded thought for nearly 1.5 millennia.
Ancient civilizations believed that Earth was flat, and covered with a spherical dome on which the Sun, Moon, planets, and stars resided. In the second century A.D., the Ptolemaic system moved Earth to the universe's center.
From the dawn of history until the beginning of the 17th century the known universe consisted of only 8 bodies: Sun Mercury Venus Earth Moon Mars Jupiter Saturn plus the "fixed" stars. In Europe, the prevailing view was the Ptolemaic system with the ...
These are the ones that can be seen easily without any optical instruments. In Europe, the prevailing view was the Ptolemaic system with the Earth at the center and the other bodies revolving around it.
The 17th Century ...
named Giordano Bruno interpreted Copernicus' heliocentric theory as a refutation of Papal authority over the Universe. This did not please the Vatican, and they burned him at the stake for it in 1600, incidentally investing the Ptolemaic system ...
 See also: Earth, Sun, Planet, Universe, Astronomy
  
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