Why Don’t We Feel the Earth Move?
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Claudius PtolemyHistorical profile·#5792·about 150 CE·AI-assisted
The Earth stands still at the center of the universe. The Moon, the Sun, and the planets circle it.
Criticized3*
Claudius PtolemyHistorical profile·#5793·about 150 CE·Criticism·AI-assisted
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.
Claudius PtolemyHistorical profile·#5794·about 150 CE·Criticism·AI-assisted
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.
Criticized1*
Johannes KeplerHistorical profile·#5807·1609·Criticism·AI-assisted
No arrangement of circles fits Tycho’s measurements of Mars. My best one still misses some of them by eight minutes of arc, far more than Tycho’s errors.