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(iii) Describe in detail how the Ptolemaic Epicycle Theory was supposed to explain the motion of Jupiter. Use Pictures too.
PTOLEMAIC EPICYCLE THEORY ON MOTIONS OF JUPITER
The following Ptolemaic sequence shows the motions of Jupiter from west to east. It is important to note that Jupiter’s looping motion according to the Ptolemaic view were “real,” while according to the Copernican system, they were “apparent.”24
1. The earth is below the equant, symmetrically opposed to C.
2. As shown below:
2.a. Jupiter’s epicycle is centered on the deferent, and Jupiter sits on the deferent relative to
the fixed stars.
2.b. Jupiter begins to travel uniformly around its epicycle, while the center of the epicycle on
its deferent travels uniformly around the equant Q.
24 Chaisson, McMillan. Astronomy Today. 7th Edition. 38. •28•
