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For the Moon, Ptolemy began with Hipparchus' epicycle-on-deferent, then added a device that historians of astronomy refer to as a "crank mechanism": [26] he succeeded in creating models for the other planets, where Hipparchus had failed, by introducing a third device called the equant. Ptolemy wrote the Syntaxis as a textbook of mathematical ...
As a measure of complexity, the number of circles is given as 80 for Ptolemy, versus a mere 34 for Copernicus. [24] The highest number appeared in the Encyclopædia Britannica on Astronomy during the 1960s, in a discussion of King Alfonso X of Castile's interest in astronomy during the 13th century.
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.
Anaximander. The main features of Archaic Greek cosmology are shared with those found in ancient near eastern cosmology.They include (a flat) earth, a heaven (firmament) where the sun, moon, and stars are located, an outer ocean surrounding the inhabited human realm, and the netherworld (), the first three of which corresponded to the gods Ouranos, Gaia, and Oceanus (or Pontos).
Al-Juzjani even proposed a solution to the problem. In al-Andalus, the anonymous work al-Istidrak ala Batlamyus (meaning "Recapitulation regarding Ptolemy"), included a list of objections to the Ptolemic astronomy. One of the most important works in the period was Al-Shukuk ala Batlamyus ("Doubts on Ptolemy"). In this, the author summed up the ...
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 ...
Messier 7 or M7, also designated NGC 6475 and sometimes known as the Ptolemy Cluster, [4] is an open cluster of stars in the constellation of Scorpius. The cluster is easily detectable with the naked eye, close to the "stinger" of Scorpius. With a declination of −34.8°, it is the southernmost Messier object.
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.