Claudius ptolemy birth and death

Claudius’ finished his first major work on astronomy was he was 50 years old. It was based on the observations he had made over the previous 20 to 30 years. He called his book, The Almagest, which meant ‘The Greatest’. In his work, Claudius described the movements of objects in the night sky using maths. He believed the paths of the stars and planets were not random. He explained them by combining several circular movements. 

In Claudius' model of the Solar System, the Earth was stationary. It was surrounded by a great sphere which carried the stars, planets, Sun and Moon around the Earth. This idea of a geocentric (Earth centred) Solar System became known as the Ptolemaic system.

The Almagest also contains a star catalogue. It listed 48 constellations which could be seen from the Northern Hemisphere. Claudius' later work, ‘Planetary Hypotheses’ was more mathematical than The Almagest. It set out the Universe as a series of spheres and estimated the distances to the Sun and the 'fixed stars'.

Claudius Ptolemaeus (circa AD 100–170), better known as Ptolemy, was a Greco-Roman astronomer, mathematician, geographer and cartographer.

He was a citizen of Alexandria, Egypt, in the 2nd century AD.

Although his writings influenced astronomy for over a millennium – not always correctly – very little is known about his life.

Ptolemy's Almagest and geocentrism

Ptolemy devoted most of his time and effort to astronomy.

His first major work was the 13-volume Almagest, meaning ‘the greatest’ and known to him as the Mathematike Syntaxis (The Mathematical Collection).

It was a synthesis of all the results obtained by Greek astronomy up to then, especially the earlier findings of Hipparchus, providing a model for astronomical functions and movements of heavenly bodies.

In the Almagest, he introduced the geocentric system, arguing that Earth was stationary at the centre of a large crystalline celestial sphere – the Universe – around which the stars and planets orbited in a broade

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