What was Ptolemys theroy about the structure of the earth?
I note several posters addressing Ptolemy’s earth-centric view of the cosmos rather than addressing the original poster’s question about Ptolemy’s thoughts on the structure of the earth (*structure*, not orbit, folks), about which next to nothing is known. Of the things we know, Ptolemy was definitely NOT a member of the Flat Earth Society. Find in the next link one of his maps of the “known world”. Observe the recognition of the spheriod shape. http://geology.cwru.edu/~huwig/catalog/s… He wrote three main works — one on astronomy and geometry, one on astrology, and finally, his 8 volume work on geography. From the latter, we know that like the other Greeks and Romans of his time, he understood that the Earth was round, and discussed at some length the problem of portraying it on a flat piece of paper (see his map, above). In addition, Ptolemy took a crack at it, but made a fairly serious underestim
Ptolemy (aka Claudius Ptolemaeus, Ptolomaeus, Klaudios Ptolemaios, Ptolemeus) lived in Alexandria (in Egypt) from approx. 87 -150 AD. Very little is known about his personal life (the image above is probably purely the artist’s imagination) He was an astronomer, mathematician and geographer. He codified the Greek geocentric view of the universe, and rationalized the apparent motions of the planets as they were known in his time. Ptolemy synthesized and extended Hipparchus’s system of epicycles and eccentric circles to explain his geocentric 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 to orbit the Earth in the 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 This is described in the book Mathematical Synt