Report Of Claudiuos Ptolemy

Claudius Ptolemy

Ptolemy (c. AD 90 – c. AD 150) was a Greco-Egyptian writer of Alexandria, known as a mathematician, astronomer, geographer, astrologer, and poet. He was born at Ptolemais Hermiou in the Thebaid, and lived in the city of Alexandria in the Roman province of Egypt, wrote in Greek, and held Roman citizenship. Regrettably there are no more facts about this brilliant physicist, beyond that. Also, he was the author of several scientific treatises, which are Almagest, includes astronomical researches, Geography and Tetrabiblos, which is an astrological treatises of horoscopic astrology.

Planetary Motion

Around 100 AD – 150 AD, Claudius Ptolemy developed an very convincing theory of planetary motion. His theory attempted to reconcile observation with a prepared theory and to keep the planet Earth at the center of the universe. Eventually in this theory, planets travel in small and perfect circles that he named epicycles while simultaneously traveling in larger circular orbits. Even though the theory came to explain many of the previous stated theories, Ptolemy´s complex model did not completely agree with observation.

His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres, in which he used the epicycles of his planetary model to compute the dimensions of the universe. He estimated the Sun was at an average distance of 1,210 Earth radii, while the radius of the sphere of the fixed stars was 20,000 times the radius of the Earth.

Astronomy

In the Almagest, Ptolemy claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations. He presented his astronomical models in convenient tables. It also contains a star catalogue. Ptolemy presented a useful tool for astronomical calculations in his Handy Tables, which tabulated all the data needed to compute the positions of the Sun, Moon and planets, the rising and setting of the stars, and eclipses of the Sun and Moon.

Geography

Ptolemy's other main work is his Geography. He demonstrates a discussion of the data and of the methods he used. Claudius assigned coordinates to all the places and geographic features he knew, in a grid that spanned the globe. Latitude was measured from the equator, as it is today, but Ptolemy preferred to express it as climata, the length of the longest day rather than degrees of arc. In the second part of the Geography, he provided the necessary topographic lists, and captions for the maps.

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