How did people begin to disprove the geocentric model?
In: Technology
So it’s pretty complicated and ELI5 is not really the best place to get a real explanation for it (this is really an /r/AskHistorians question). I am writing this as a professional historian of science, for whatever that is worth.
The basic thing to keep in mind is that they didn’t _disprove_ it. What happened is that a _better_ model was eventually developed, over hundreds of years, and many observations accumulated that fit with that model better. And so a heliocentric model _displaced_ it.
And along with that, they also developed the physics that was necessary for a moving Earth to even be imaginable — if you don’t have a concept of inertia or reference frames, for example, it’s pretty hard to imagine that the best explanation is one where the Earth is traveling at tens of thousands of miles per hour (while rotating at about 1,000 miles per hour) and somehow we don’t feel it (or fly off).
If one were to track the main steps on the way to a successful heliocentric model, they would be:
* Kepler’s orbital dynamics, which for the first time made the Copernican model actually fit the data, and at the same time eliminated the crystalline spheres concept that was common to both the Copernican and Ptolemaic systems.
* Galileo’s observation of the phases of Venus, which convinced even the Catholic Church that the Ptolemaic system did not fit observational data (they replaced it with the geocentric Tychonic model instead).
* The gradual development of the physics of motion and theories of gravity, which culminated in Newtonian mechanics, which basically made it entirely clear that anything other than a heliocentric system was a bizarre contrivance and not very useful, and provided all of the physics you need to explain why we don’t fall off of the planet, what holds the system in place, and so on.
Which _isn’t_ what your astronomy textbook will say (they’ll say: Copernicus, Kepler, Galileo, done). But your astronomy textbook is not a history textbook and things are more complex than astronomy textbooks tend to let on. There are a lot of observations that are typically mentioned (moons of Jupiter, observation of stellar parallax) which were not especially convincing at the time, at least not compared to the factors mentioned above. They make for a nice story but are bad history.
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