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In Ptolemy's system the planets orbit the Earth and not the Sun. How did the system explain the retrograde motion of planets like Jupiter?- the Sun moved among the planets, and pulled them out of their circular orbits- the planets were not moving along the ecliptic but all over the celestial sphere- the planets moved in very elongated ellipses, and their speed in orbit changed radically over the course of a year- you can't fool me, Ptolemy's system did not include ANY explanation of retrograde motion- the planets moved on a small circle whose center, in turn, circled a point near the Earth

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