What if Ptolemy's theory was Heliocentric than Geocentric?

What would the effects be on history if the theory were put forth by Ptolemy than Copernicus?


  • Total voters
    16

All Rounder

Gone Fishin'
Not whole lot more to say than what would happen if his theory on the earth's position in the solar system was a very rough version of Copernicus's theory?
 
I'd say neutral. I don't see many issues where it would make an sizable impact until serious astronomical work is being done after the invention of the telescope.
 
Negative. Ptolemy's advantage was that he was a quite accurate scientist. However, ancient oberservations and theories suggested that the earth is the centre of the universe, so if Ptolemey had asserted the contrary, he would have left the path of science and entered speculation; he might have lost scientific authority.
 
I go with neither positive or negative. Aristarchus of Samos advanced the heliocentric theory (according to a later text by Archimedes) but that was ignored in favour of both Aristotle and Ptolemy. Aristotle's theories were well regarded, so Ptolemy's strange heliocentric theory would just be ignored as an aberation (i.e. one of his 'off-days' which is patently wrong to anyone who just looks at the sky - in the mediaeval view).
 
The problem was that people thought that celestial bodies must move in perfect circles, which isn't actually the case. Perfect circle heliocentric and geocentric models both had problems perdicting the location of celestial bodies and relied on epicycles to explain some differences Copernicus' map had some because of the perfect circles not allowing good prediction, though it did much better at explaining several aspects of planetary motion.

Basically unless Ptolemy somehow got good enough optics to get the observational evidence of Galileo (Jupiter's moons and Venus' phases) or developed Keplar's math most people would go with their eyes. They would only go with the model if it was better at predicting the location of bodies.
 

All Rounder

Gone Fishin'
The problem was that people thought that celestial bodies must move in perfect circles, which isn't actually the case. Perfect circle heliocentric and geocentric models both had problems perdicting the location of celestial bodies and relied on epicycles to explain some differences Copernicus' map had some because of the perfect circles not allowing good prediction, though it did much better at explaining several aspects of planetary motion.

Basically unless Ptolemy somehow got good enough optics to get the observational evidence of Galileo (Jupiter's moons and Venus' phases) or developed Keplar's math most people would go with their eyes. They would only go with the model if it was better at predicting the location of bodies.

Well ITTL he did just that and founded the theory.
 
Ancient Greeks discovered the relative sizes of the sun and the moon through trigonometry, but they still believed in geocentrism.

It's hard to let go of an idea so entrenched that almost everyone thinks its true, even when it isn't.
 
Given the state of scientific knowledge at the time, geocentrism was the better-supported theory. It wasn't until later that we were able to adequately explain why, if the Earth revolves around the Sun, there seems to be no stellar parallax (it wasn't until the 19th century that astronomical instruments got powerful enough to observe it), why there aren't continuous strong winds constantly blowing westwards, why birds hovering in the air don't appear to shoot westwards as the grounds revolves under them, etc. So unless Ptolemy also managed to solve these difficulties, his theory would likely be no more successful than Aristarchus'.
 
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