At 2nd century, Claudius Ptolemy published a treatise on astronomy titled Hè magalè syntaxis, which in Arabic became known as Almagest. The work includes an extensive list of stars, explains the apparent movement of the stars and offers the description of a geocentric system (which locates the Land in the center of the universe).

AlmagestTo develop your treatise, Ptolemy started from a catalog of stars that I had created Hipparchus of Nicaea. The Almagest presents thirteen volumes, beginning with the exposition of the geocentric system and ending with a detail of the method followed by the author to calculate the trajectories and positions of the planets.

Ptolemy provides information on forty-eight constellations in the Almagest. The astronomer also exposes the foundations of the geocentric system, with the planets, the Moon and the Sun revolving around the Land.

It is important to mention that Ptolemy wrote his book in Greek. At 9th century, the caliph Al-Mamun promoted the translation of the text into Arabic, which came to be referred to as Al-Majisti (translatable as “The biggest”). Finally the work went down in history as Almagest.

The popularity of Almagest in the western world it came through its Arabic version. Just in the XII century the Almagest was translated into our tongue.

It should be noted that the geocentric system that postulated Ptolemy was the theory predominant to explain the orbits of the planets until Copernicus proposed the heliocentric model. Later, Galileo Galilei and Johannes kepler they contributed more data that consolidated the heliocentrism.