Ptolemy believed that the earth was at rest in the center of the universe. Seen from the earth, there are the moon, mercury, Venus, the sun, Mars, Jupiter and Saturn in turn, orbiting the earth in their respective circular orbits. Among them, the motion of the planet is more complicated than that of the sun and the moon: the planet moves on this circle, and this circle runs around the earth along a uniform wheel. Beyond the sun, moon and planets, there is a celestial sphere inlaid with all the stars-the starry sky. Outside, it is the primitive earth that drives the movement of celestial bodies.
Geocentric theory is the first planetary system model in the world. Although it is wrong to regard the earth as the center of the universe, its historical achievements should not be obliterated. Geocentric theory recognizes that the earth is "spherical" and distinguishes planets from stars, focusing on exploring and revealing the laws of planetary motion, which marks a great progress in human understanding of the universe. The most important achievement of geocentric theory is to calculate the motion of planets by mathematics. Ptolemy also put forward the concept of "orbit" for the first time, and designed a flow-even wheel model. According to this model, people can quantitatively calculate the motion of planets and guess the position of planets, which is an amazing creation. In a certain period of time, according to this model, the astronomical phenomena can be predicted correctly to a certain extent, so it also plays a positive role in production practice.
After all, Ptolemy pieced together the wheel-even wheel model in the current geocentric theory based on limited observation data. He made the model consistent with the measured results by artificially specifying the dimensions of the current wheel and even wheel and the running speed of the planet. However, in the late Middle Ages, with the continuous improvement of observation instruments, the measurement of planetary position and motion became more and more accurate, and the deviation between the observed actual position of the planet and the calculated results of this model gradually appeared.
Those who believe in geocentric theory do not realize that this is caused by the error of geocentric theory itself, but use the method of adding this round to remedy geocentric theory. At first, this method can barely cope. Later, the number of small wheels increased to more than 80, but the exact position of the planet could not be calculated satisfactorily. This cannot but make people doubt the correctness of geocentric theory. /kloc-in the 6th century, Copernicus finally founded the "Heliocentrism" on the basis of the enthusiasm of ancient Greek ancestors and contemporary scholars for the sun. Since then, geocentric theory has been gradually eliminated.