Talk:General Astronomy/Apparent Motions of the Planets

Ptolemy used this concept. He may have acquired it from earlier astronomy in Sumer (Iraq today)which was being developed as early as 2600 B.C.E. There is evidence on a copper bowl acquired by Prof. Clyde Hostetter in Riyadh in September 1976. It has non-verbal symbology about eclipses and also about the movements of the planet Venus, the manifestation of the sky-goddess Inana, who was an important part of Sumerian religion. Some of the symbols etched in the bowl indicated that Venus could be seen (without optics) as a thin crescent just before and just after inferior conjunction -- when Venus passes between the Earth and the Sun. Included in the symbology are a circle of loops suggesting that during the retrograde motion of Venus the planet came closer to the Earth. This could have suggested to Ptolemy the concept of epicycles, since he had access to the astronomical records of the Sumerians. Details and photos of the symbology on the bowl can be obtained on request from Professor Hostetter at chostett@verizon.net.

Maybe you can address what other drawbacks there were to the epicycle theory, other than inefficiencies, if there were any...