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An interesting tangent: At the time of Gallielo, the church used the Tychonian model of the solar system. In the Tychonian model, the earth is the center and t
by goto11 7y ago
An interesting tangent: At the time of Gallielo, the church used the Tychonian model of the solar system.
In the Tychonian model, the earth is the center and the sun revolves around the earth. But the other planets revolve around the sun! You will notice this is practicallty the same model as the Copernican model except for the arbitrary definition of what is "the center".
The only observable difference was the relation to the firmament which in the Tychonian model revolved around the earth but in the Copernican revolves around the sun. If the Copernican model was correct, some parallax to the stars should be observable. Now we know this is not observable due to the distance to the stars, but this was not known at the time.
- fjsolwmv 7y agoIt's not arbitrary. The only two choices that work are the real center of gravity, and the observer's position with the real center of gravity orbiting the observer and everything else orbiting the real center of gravity. If Tycho chose Jupiter as the center of the orbits, the planetary orbits would have the same problem of epicycles as the older models.
- Armisael16 7y agoWhat precisely do you mean by “the same problem with epicycles”? You can fix Jupiter at the origin. You use exactly the same equations, except that the sun is using the equation that used to describe Jupiter (with an extra negative sign) and the other planets add in the term describing the Sun’s motion. Earth is no different than any other planet (or other celestial body in a stable orbit relative to the solar system) in this respect. Hell, you could make the Moon the center of the solar system - the math works just fine.
- rimliu 7y agoIf observer is on the Earth then equations for Jupiter will not work for describing the apparent motion of the planets.
- goto11 7y agoYou can claim that any arbitrary point is "the center of the universe" if you acknowledge that the planets rotate around the sun, not around the designated "center". If you choose Jupiter as the "center", there would still be no observable difference and you wouldn't need additional epicycles.
- ndm000 7y agoAn interesting read is On the Revolutions of Heavenly Bodies by Copernicus, even if you just read the introduction. It’s an appeal to the Pope regarding the scientific nature of his conclusions. Regardless, they still excommunicated him years later for going against what was thought the authority of scripture.
- simplesleeper 7y agono, Copernicus was never excommunicated, although "On the Revolutions of Heavenly bodies" went through various stages of requiring errata pointing out it was only a hypothesis and even a ban
- goto11 7y agoHe was never excommunicated as far as I know, and the book was only published after his death. The church did suppress the book though.
- ndm000 7y agoThanks - I was confusing the stories of Copernicus and Galileo. Galileo’s works, based on Copernicus’s ideas, were declared heretical. While not excommunicated he was persecuted by the church. https://en.m.wikipedia.org/wiki/Galileo_affair https://en.m.wikipedia.org/wiki/Galileo_affair
- brighter2morrow 7y ago>An interesting read is On the Revolutions of Heavenly Bodies by Copernicus, even if you just read the introduction. It’s an appeal to the Pope regarding the scientific nature of his conclusions. Regardless, they still excommunicated him years later for going against what was thought the authority of scripture. This... is completely false. Copernicus never faced adversity for his heliocentric model.
- simplesleeper 7y agothis isn't entirely true. At the time of Galileo, Tycho was presenting his model (and was a militant enemy of Galileo). Tycho's model was either used or not depending on more local scientific stances, but it wasn't entirely popular.