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An edition in Latin of the Almagestum in 1515. The Almagest (/ ˈ æ l m ə dʒ ɛ s t / AL-mə-jest) is a 2nd-century mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy (c. AD 100 – c. 170) in Koine Greek. [1]
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 ...
The triquetrum (derived from the Latin tri-["three"] and quetrum ["cornered"]) was the medieval name for an ancient astronomical instrument first described by Ptolemy (c. 90 – c. 168) in the Almagest (V. 12). Also known as Parallactic Rulers, it was used for determining altitudes of heavenly bodies.
The first major Arabic work of astronomy is the Zij al-Sindh by Muhammad ibn Musa al-Khwarizmi. The work contains tables for the movements of the Sun, the Moon, and the five planets known at the time. The work is significant as it introduced Ptolemaic concepts into Islamic sciences. This work also marks the turning point in Arabic astronomy.
c. 150 CE – Claudius Ptolemy completes his work Almagest, that codifies the astronomical knowledge of his time and cements the geocentric model in the West, and it remained the most authoritative text on astronomy for more than 1,500 years.
A printed map from the 15th century depicting Ptolemy's description of the Ecumene. (1482, by Nicolaus Germanus) Claudius Ptolemy (90–168 AD) lived in Alexandria, the centre of scholarship in the 2nd century. In the Almagest, which remained the standard work of astronomy for 1,400 years, he advanced many arguments for the spherical nature of ...
Ptolemy argued that the Earth was a sphere in the center of the universe, from the simple observation that half the stars were above the horizon and half were below the horizon at any time (stars on rotating stellar sphere), and the assumption that the stars were all at some modest distance from the center of the universe.
Greek astronomers such as Geminus [1] and Ptolemy [2] recorded these classical planets during classical antiquity, introducing the term planet, which means 'wanderer' in Greek (πλάνης planēs and πλανήτης planētēs), expressing the fact that these objects move across the celestial sphere relative to the fixed stars.