Why Don’t We Feel the Earth Move?
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See chronicleThe Earth stands still at the center of the universe. The Moon, the Sun, and the planets circle it.
Ptolemy’s system has to set by hand that Mercury and Venus never stray far from the Sun, and that the outer planets loop backward just when they’re opposite the Sun in the sky. It never explains why. If the Earth and the planets all circle the Sun, both follow.
Every so often, a planet seems to stop, drift backward among the stars for weeks, and then move on. A planet that simply circled the Earth would never do that.
Each planet rides on a small circle, an epicycle, whose center travels along a larger one around the Earth. On the near side of its epicycle, the planet moves against the larger circle’s motion, so it seems to drift backward.