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Sep 17 at 0:37 comment added Francis Davey Note that Ptolemy didn't need to use many levels of epicycles, because he used eccentrics and equants - i.e. his basic model was not based on uniform circular motion (in fact accurate to an elliptic model to first order in the eccentricity). He needed epicycles primarily to centre the model on the Earth, so most of those epicycles are really the Earth's orbit to a circular approximation. He did have two counter-rotating circular orbits in one part of his model, but they are equivalent to an ellipse.
Oct 12, 2022 at 6:45 vote accept thetrueembodimentofstupidity
Sep 18, 2022 at 13:42 comment added Barmar Not only are epicycles more complex, but they also probably defy explanation of what causes them. Whereas Newton's laws of motion and gravity are mostly sufficient to explain the heliocentric system.
Sep 17, 2022 at 13:22 history edited Philip Wood CC BY-SA 4.0
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Sep 17, 2022 at 13:16 comment added Philip Wood But couldn't you give the same reference frame different co-ordinate systems, e.g cartesian axes and cartesian axes at different angles from the first set?
Sep 17, 2022 at 13:02 history edited Philip Wood CC BY-SA 4.0
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Sep 17, 2022 at 12:06 comment added StephenG - Help Ukraine I would suggest adding that a reference frame is simply a coordinate system.
Sep 17, 2022 at 11:18 history edited Philip Wood CC BY-SA 4.0
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Sep 17, 2022 at 10:25 history answered Philip Wood CC BY-SA 4.0