Definition of ptolemy Ptolemy

/tɑˈlʌmi/ - [talumee] - Ptol•e•my

We found 3 definitions of ptolemy from 3 different sources.

What does ptolemy mean?

WordNet

Noun
ptolemy - Alexandrian astronomer (of the 2nd century) who proposed a geocentric system of astronomy that was undisputed until the late Renaissance
		Claudius Ptolemaeus

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Wikipedia

Ptolemy is the English name for Claudius Ptolemaeus. He was a Greek who probably lived and worked in Alexandria, in Egypt. He lived from about 85 to 165 A.D. He is famous for his work on astronomy and geography.

Very little is known about his personal life.

He was an astronomer, mathematician, and geographer. He described in his writing the Greek or geocentric view of the universe. The Greeks thought that the Earth was the center of the universe. He also thought out and described the apparent motions of the planets as they were known in his time.

Ptolemy explained and extended Hipparchus's system of epicycles and eccentric circles to explain his geocentric (Earth-centered) theory of the solar system. Ptolemy's system involved at least 80 epicycles to explain the motions of the Sun, the Moon, and the five planets known in his time. He believed the planets and sun moved around the Earth in this order: Mercury, Venus, Sun, Mars, Jupiter, Saturn.

This system became known as the Ptolemaic system. It predicts the positions of the planets accurately enough for naked-eye observations, so it seemed accurate at the time. This is described in his book "Mathematical Syntaxis" (widely called the "Almagest"), a thirteen-book mathematical treatment of the phenomena of astronomy. It contains a wide variety of information ranging from earth conceptions to sun, moon, and star movement as well as eclipses and an explanation of the length of months. The Almagest also included a star catalog cont