There was one strong issue with the Ptolemaic model – it didn’t adequately explain the retrograde motions of the planets, even with epicycles. This is what lead Copernicus to propose the ...

It is often claimed that, by the 16th century, this Ptolemaic model of the universe had become so laden with these epicycles that it was on the point of falling apart. Then along came the Polish ...

Forbes contributors publish independent expert analyses and insights. The Universe is out there, waiting for you to discover it. The Ptolemaic model, where the Earth was stationary, and everything ...

Ibn al-Shatir’s Mercury model, with its multiplication of epicycles to eliminate eccentrics ... as well as penetrating critiques of Ptolemaic astronomy. Ibn al-Shatir’s use of the Tusi ...

For one, it came at a time when European astronomers were struggling to resolve the mathematical and observational problems that arose out of the then-accepted Ptolemaic model of the universe ...

as today’s equivalent of the Ptolemaic epicycles, the convoluted tweaks made to the model of the planets’ motions to maintain the fiction that they were all revolving around Earth. I have more ...