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There was also a third camp at the time: Jesuits.

Apparently Galileo met with Jesuit astronomers at the Vatican Observatory, and they suggested he might save both scientific evidence and theological correctness by adopting the Tychonic system, where the center of the universe is still the earth, but all the planets revolve around the sun, which revolves around the earth.

As it turns out, we now know that both the Copernican and the Tychonic are exactly equally wrong.




I don't think they were exactly equally wrong. The Tychonic system doesn't quite predict stellar parallax, for example. I'd say it's the worse model of those two.

And it looks less pretty on pictures, too.

EDIT: Ironically, the lack of observable (at the time) parallax was reportedly used by Tycho Brahe to argue against heliocentrism, because "stars obviously can't be far enough to make prallax unobservable". Now, that's clearly wrong.


Tycho Brahe was wrong but on stronger scientific ground given the observations available, stellar parallax wasn't observed until around 1806 by Giuseppe Calandrelli and not definitively measured until 1838 by Friedrich Bessel.


Tycho Brahe was wrong but on stronger scientific ground given the observations available

Depends on how much weight you place on different lines of reasoning.

One of Galileo's key insights was that there's no fundamental difference between the terrestrial and the celestial. In contrast, the Aristotelian heavens are made of aether, in part to be able to account for the diurnal motion of far-distant planets and stars.


Everything goes around everything else, unless you want to bring back the aether. So they are both right - there are no special points except the one you choose as your FoR, you can choose earth-centric, heliocentric, pluto-centric, galactic-centre-centric, local-cluster-centric - none of them are wrong.


Except that the center of mass of Solar System lies within or very close to the Sun, so in most practical reference frames it looks pretty much spot on heliocentric. OTOH the only reasonable frame producing geocentric view is the Earth.


You can do the calculations from a different point, CoM makes things easier. It's only mathematically simple, not really objectively special except within a chosen context.


"As it turns out, we now know that both the Copernican and the Tychonic are exactly equally wrong. "

It seems to me that one is less wrong than the other. In particular one was a significantly better fit for the evidence available at that time.

edit: typo




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