I was thinking today that considering how obsessed the Ancient Greeks were with exploring geometry ideas, it's surprising they didn't figure out Heliocentrism. Eratosthenes figured out a reasonable estimate of the size of the Earth, so clearly they were thinking a lot about Earth/Sun systems. According to Wikipedia, a lost work by Aristarchus may have suggested Heliocentrism, but why didn't this gain more traction? It pretty much explained everything about the motion of the planets, as Copernicus eventually realized. It seems like the Greeks had all the pieces in place, or was their a key piece of knowledge they didn't have that I'm not realizing?
Copernicus worked out his model with tools and mathematics little better than the Greeks. Interestingly the Greeks and Copernicus were both missing the same knowledge. They were also working against the same logical problem. Ptolemy who created the geocentric model in use from about 200 BC to 1500 AD had several iron clad arguments that made a heliocentric model ridiculous.
If the earth moves around the sun and spins.
why doesn't everybody fly off?
Why do arrows come straight back down?
Why do we not feel an enormous gale as we move with tremendous velocity around the sun?
How do you explain the seasons with a heliocentric model?
Copernicus figured out the heliocentric model and used it to calculate the positions of stars. He found that his model was superior to the geocentric model that was standard at the time. But he didn't want to rock the boat so he kept his model to himself. He became famous for the accuracy of his astronomical predictions. Only his closest friends and colleagues knew the dark secret of his amazingly accurate heavenly predictions. Finally, toward the end of his life his friends convinced him to publish the model that allowed him to be the most accurate astronomer in Europe despite his rudimentary tools.
The book came out and just after Copernicus death unknown to Copernicus a forward was included in the book labeling his model as hypothetical not as a declaration of truth. This allowed scientists to use his model to accurately predict the position of stars without making the ridiculous claim that the earth rotated around the sun.
Fast forward to 1632. Galileo introduces the world to inertial frame of reference. For those who don't know Inertial frame of reference is the motion of an object relative to the motion of another object as opposed to motion from an absolute reference frame. Think of a man running at 10 mph around a ship that is moving at 17mph. To somebody standing on shore the man is moving at 27mph. To somebody on the ship the man is moving at 10mph. Anyway, once this concept is understood 3 of Ptolemy's arguments are overcome.
Fast forward to 1687 and Isaac Newton introduces the Law of Universal Gravitation. This is the final piece in the puzzle that explains how people stick to the earth and the sun and earth spin around each other. (By the way the earth does not go around the sun, the earth and sun spin around a common center)
The knowledge the Greeks didn't have was Gravity and inertial frame of reference. Copernicus succeeded where others failed because he didn't try to convince people that the earth went around the sun. Instead he invented the best way to predict the motion of the stars and then told people the way to do it was to imagine the earth went around the sun. Later scientists established why the "hypothetical" heliocentric system worked.
The Gradual Acceptance of the Copernican Theory of the Universe