spherical Copernican heliocentric geocentric egocentric Ptolemaic flat infinate plane

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1. I typed a long comment that delved into the subject of Newtonian mechanics and the history behind the discoveries. This comment was lost because my hand accidentally clicked the touchpad and loaded another video.
   
   In short, the observation on the right is the actual true observation of planetary motion measured from earth. It is oversimplified so the orbits appear to overlap, but of course when scaled to distances the orbits of the true planets never would intersect because, for lack of a better reason, we don't observe them intersecting. I wouldn't use this to talk to people who believe in geocentrism.
   
   The advent of heliocentrism came with the revelation that the movement of the planets were so much simpler when we modeled planetary motion around the sun instead of around earth. The fact that they "loop" or "backtrack" stops being a problem when we take into account a revolving Earth as our point of reference.
   Ancient people could start with Sun-centered universe and model planetary motion "roughly" okay by taking the relative positions and reverse engineering the view of the planets we should get from our reference point on Earth (basically moving from the left picture to the right one mathematically.) It was good, but not perfect. However, that was the first step to getting something close to a predicting model of reality.
   
   Newtonian gravitation greatly increased the accuracy of the previous heliocentric model that assumed that planetary motion was circular. Now you can translate from the elliptical orbiting model to the "geocentric" model to predict the position of a planet in the sky at any one point in time. That's where you have to get them-- they may be smart enough to know that nobody even in the past observed crossing orbits but they couldn't model the motion at all mathematically from a purely geocentric system. You have to go backwards from a Newtonian heliocentric model to gain any accurate prediction of planetary motion from the standpoint of the Earth. We can probably model geocentric planetary motion for the next few thousand years and write a function that does it accurately just with numbers, and it will match perfectly to observation, but the only way we can do this is by reverse engineering the elliptic heliocentric model-- we wouldn't have the predictive capacity without it.
   Sorry for the text wall. I'm looking for distractions from homework.
2. is gravity real or does the earth suck ?