Objecting to those who consider Copernicus’s work as repeating the achievements of Antiquity, we pay attention to his determination of uniform time necessary for applying any mathematical theory in particular, the one describing the observed uneven movements through a composition of circular and uniform rotations. Using the Egyptian year of 365 solar days, Copernicus analyzed the observations for the period from the first Olympiad up to his own observations. Generalizing the results of observations of two millennia and reducing them to the unique time system enabled his explaining the observed precession of equinoxes, and changes in the angle of inclination of the Earth’s equator to ecliptic by the lag of the Earth’s center rotation from that of its axis, simultaneously to exclude empty spheres from the medieval mechanical models of the Universe. Analyzing the observations of the period 4 times longer than that of Ptolemy, Copernicus managed to obtain the mean value of precession and the period of the Earth axis rotation practically coinciding with modern determinations. The proof of “the triple motion of the Earth” was necessary for affirmation of heliocentric system of the world.