Claudius Ptolemy lived in Alexandria in the second century CE and was a Greco-Egyptian scholar. He was not only known as a mathematician, astronomer, geographer but also as an astrologer and a poet in the Greek Anthology. Ptolemy wrote a number of scientific treatises. He was the author of “The Almagest,” an astronomical treatise.
The Almagest is the only complete astronomy treatise believed to have survived from antiquity. Ptolemy said that he derived his geometrical models from selected astronomical observations, which he said came from Aristotle’s geocentric universe. A star catalogue and a list of 48 constellations are included in the Almagest.
Ptolemy's planetary hypotheses
The theories proposed by Ptolemy outperformed the Almagest’s mathematical model. It sought to depict the world as a series of nested spheres in physical form. His model was geocentric (referring to Earth as the centre of the universe), and it was almost universally accepted before heliocentric models were created.
He provided astronomers with a valuable method in his Handy Tables. The tool tabulated all of the information required to calculate the locations of the Sun, moon , planets, rising and setting stars, and solar and lunar eclipses. Later astronomical tables, or ‘zijes,’ as they were named by Islamic astronomers, were based on these.
Claudius Ptolemy is named after Claudius, the Roman who granted Ptolemy Roman citizenship. According to the timeline, this was most likely Claudius, the Roman Emperor.