Which ancient thinker authored the book "Almagest"?

The book "Almagest" was authored by Ptolemy, a prominent ancient Greek mathematician, astronomer, and geographer who lived in Alexandria during the 2nd century AD. In "Almagest," Ptolemy presented a comprehensive geocentric model of the universe, which was the dominant astronomical paradigm for over a millennium. His work detailed the motion of the stars and planets and introduced mathematical techniques to predict celestial phenomena.

Ptolemy's influence was immense, as his theories shaped the development of astronomy in both the Western and Islamic worlds. This work was foundational for later astronomical models until the Copernican revolution introduced heliocentric ideas. Understanding Ptolemy's contributions is crucial for grasping the evolution of astronomical thought in Western civilization.