In a gorgeous animation, Malin Christersson shows how much simpler it is to plot out celestial mechanics when you assume that all the bodies in our solar system are in orbit around the sun, rather than the other way around.
Given the lack of a universal reference point, it's not exactly true that anything goes around anything else — you can plot out the universe as though any point in it were stationary and everything else was moving in reference to it. But when you adopt the heliocentric model, the number of equations you have to do in order to make sense of things drops by an enormous amount, to the point where it's hard to imagine why anyone wouldn't want to default to this model.
My dear old friend Possum Man told me about a trig class in his Waldorf school where the teacher showed them how to calculate the position of the planets in a geocentric universe, to drive home the real meaning of relativity.
Christersson's graph is part of a great potted history of geocentrism and heliocentrism, itself part of a self-directed tutorial on trigonometry.
Trigonometry – Heliocentrism and Geocentrism [Malin Christersson]
(via Bruce Sterling)