What is "almagest"

Almagest \Al"ma*gest\, n. [F. almageste, LL. almageste, Ar. al-majist[=i], fr. Gr. ? (sc. ?), the greatest composition.] The celebrated work of Ptolemy of Alexandria, which contains nearly all that is known of the astronomical observations and theories of the ancients. The name was extended to other similar works. [1913 Webster] ||

late 14c., title of a treatise on astronomy by Claudius Ptolemy of Alexandria, extended in Middle English to other works on astrology or astronomy, from Old French almageste (13c.), from Arabic al majisti, from al "the" + Greek megiste "the greatest (composition)," from fem. of megistos, superlative of megas "great" (see mickle). Originally titled in Greek Megale syntaxis tes astronomios "Great Work on Astronomy;" Arab translators in their admiration altered this.

n. A comprehensive treatise on astronomy, alchemy, geography and/or mathematics (originally compiled by Ptolemy circa 150 (C.E.)).

The work known as the Almagest, named in Greek (), and also called the Syntaxis Mathematica, is a 2nd-century Greek mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy (, Klaúdios Ptolemaîos; ). One of the most influential scientific texts of all time, its geocentric model was accepted for more than twelve hundred years from its origin in Hellenistic Alexandria, in the medieval Byzantine and Islamic worlds, and in Western Europe through the Middle Ages and early Renaissance until Copernicus.

The Almagest is the critical source of information on ancient Greek astronomy. It has also been valuable to students of mathematics because it documents the ancient Greek mathematician Hipparchus's work, which has been lost. Hipparchus wrote about trigonometry, but because his works appear to have been lost, mathematicians use Ptolemy's book as their source for Hipparchus's work and ancient Greek trigonometry in general.

The treatise was later titled (, "The Great Treatise"; ), and the superlative form of this (, megiste, "greatest") lies behind the Arabic name , from which the English name Almagest derives. The Arabic name is important due to the popularity of a Latin re-translation made in the 12th century from an Arabic translation, which would endure until original Greek copies would re-surface in the 15th century.

Ptolemy set up a public inscription at Canopus, Egypt, in 147 or 148. The late N. T. Hamilton found that the version of Ptolemy's models set out in the Canopic Inscription was earlier than the version in the Almagest. Hence it cannot have been completed before about 150, a quarter century after Ptolemy began observing.

Almagest is a peer-reviewed academic journal that publishes contributions evaluating scientific developments. Almagest addresses the philosophical assumptions behind scientific ideas and developments and the reciprocal influence between historical context and these phenomena. The journal is abstracted in the Philosophy Research Index, STEP - Science and Technology in the European Periphery and LibTOC.