Lmao I was lowkey being unserious when I said this but I have my reasons. Hellenistic scientists believed in a spherical universe, and Ptolemy derived geometric models in order to explain and predict the motion of the heavens. This is Ptolemy's Epicyclic System. - ThreadSky

akil-carta.bsky.social • 2 days ago

Lmao I was lowkey being unserious when I said this but I have my reasons. Hellenistic scientists believed in a spherical universe, and Ptolemy derived geometric models in order to explain and predict the motion of the heavens. This is Ptolemy's Epicyclic System.

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akil-carta.bsky.social•2 days ago

The model was based on the geocentric assumption of a moveable heaven revolving around a stationary earth, but it sought to explain the retrogradity of the planets. This model worked reasonably well, that it was the standard model for almost 1400 years, until Copernicus proposed something else.

akil-carta.bsky.social•2 days ago

As a planet moves around on its epicycle, the center of the epicycle (called the ``deferent'') moves around the Earth. When its motion brings it inside the deferent circle, the planet undergoes retrograde motion.

akil-carta.bsky.social•2 days ago

In the middle of it being retrograded, the planet is closest to the Earth in its cycle. The heavens were seen as pure and unchanging, while the earth was seen as changeable and corruptible. Retrogrades were seen as an affliction because their motion stopped and switched direction and speed abruptly.

akil-carta.bsky.social•2 days ago

The superior planets oppose, and rise/set against the Sun who maintains the order of motion. Somewhere in the retrograde cycle, the inferior planets rise/set in the morning, when evening is preferred. This is why I said that they are upside down, because the regular order of the heavens is disrupted

akil-carta.bsky.social•2 days ago

But it should be noted that, traditionally, an upside down planet was used to illustrate a planet in its fall, and not retrograded. Both are afflictions but they manifest differently.

akil-carta.bsky.social•2 days ago

We no longer believe in a geocentric universe, and our modern models reflect this. This is the heliocentric model on the left, compared to the geocentric model on the right.

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