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Book XII covers stations and retrograde motion, which occurs when planets appear to pause, then briefly reverse their motion against the background of the zodiac. Ptolemy understood these terms to apply to Mercury and Venus as well as the outer planets. Book XIII covers motion in latitude, that is, the deviation of planets from the ecliptic ...
Opening chapter of the first printed edition of Ptolemy's Tetrabiblos, transcribed into Greek and Latin by Joachim Camerarius (Nuremberg, 1535).. The commonly known Greek and Latin titles (Tetrabiblos and Quadripartitum respectively), meaning 'four books', are traditional nicknames [24] for a work which in some Greek manuscripts is entitled Μαθηματικὴ τετράβιβλος ...
Newton was known for his book The Crime of Claudius Ptolemy (1977). In Newton's view, Ptolemy was "the most successful fraud in the history of science". Newton claimed that Ptolemy had predominantly obtained the astronomical results described in his work The Almagest by computation, and not by the direct observations that Ptolemy described.
The angular rate at which the epicycle traveled was not constant unless he measured it from another point which is now called the equant (Ptolemy did not give it a name). It was the angular rate at which the deferent moved around the point midway between the equant and the Earth (the eccentric) that was constant; the epicycle center swept out ...
The book was thoroughly illustrated along with observations and descriptions of the stars, their positions (copied from Ptolemy's Almagest with the longitudes increased by 12° 42' to account for the precession), their magnitudes (brightness) and their color. Notably, al-Sufi improved upon Ptolemy's system for measuring star brightness.
The Ptolemaic order of spheres from Earth outward is: [5] Moon; Mercury; Venus; Sun; Mars; Jupiter; Saturn; Fixed Stars; Primum Mobile ("First Moved") 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 ...
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 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 ...