Ptolemy Publishes the Almagest

Around 150 CE, Claudius Ptolemy compiled the Mathematike Syntaxis in Alexandria, Egypt, later known as the Almagest. This 13-volume astronomical treatise presented a geocentric model with Earth at the center and celestial bodies moving in circular patterns. The work contained star catalogs, planetary theories, and mathematical models using epicycles to explain movements of the Sun, Moon, planets, and stars. The Almagest served as the standard astronomical text for approximately 1,500 years across Europe, Byzantium, and the Islamic world until Copernicus's heliocentric model replaced it in the 16th century.