Commentarlious written by Copernicus and sent to his closest friends:

"However, what Ptolemy and many others proclaimed was in line with the figures, but it also raised considerable doubts. These translations were not enough without the additional introduction of some fictitious equalizing circles, which showed that the planet does not move at the same speed either on its lifting sphere or in relation to the centre of its epicycle. Such a system therefore seemed neither sufficiently perfect nor sufficiently consistent with reason. In view of these deficiencies, I often wondered whether it would not be possible to invent a more rational system of wheels on which all the apparent inequalities of motion would depend and which would rotate uniformly in relation to their own means, as required by the principle of perfect motion."



6 axioms of heliocentric theory:

  1. There is no single center of all blue circles or spheres. The center of the Earth is not the center of the Universe, but only the center of gravity and the center of the moon sphere.
  2. All spheres circulate the Sun as their center and therefore the Sun is the center of the entire Universe.
  3. The ratio of the Earth's distance from the Sun to the height of the firmament is much smaller than the ratio of the Earth's radius to its distance from the Sun, so the distance between the Earth and the Sun is negligible compared to the height of the firmament.
  4. Whatever movement is seen on the firmament, it does not come from some kind of firmament movement, but from the Earth movement. The Earth, together with the elements surrounding it, makes a full daily rotation around its fixed poles, while the firmament and the highest sky remain motionless.
  5. What is presented to us as a movement of the Sun does not come from its movement, but from the movement of the Earth and our sphere with which we circulate around the Sun, just like any other planet. The Earth therefore has more than one movement.
  6. The horizontal, straight and backward motion of the planets comes not from their motion, but from the motion of the Earth.