Copernican system, first modern European theory of planetary motion that was heliocentric, i.e., that placed the sun motionless at the center of the solar system with all the planets, including the earth, revolving around it. Copernicus Copernicus, Nicholas (kōpûr`nĭkəs), Pol. Mikotaj Kopérnik, 1473–1543, Polish astronomer.
..... Click the link for more information. developed his theory in the early 16th cent. from a study of ancient astronomical records. He retained the ancient belief that the planets move in perfect circles and therefore, like Ptolemy Ptolemy (Claudius Ptolemaeus), fl. 2d cent. A.D., celebrated Greco-Egyptian mathematician, astronomer, and geographer. He made his observations in Alexandria and was the last great astronomer of ancient times.
..... Click the link for more information. , he was forced to utilize epicycles to explain deviations from uniform motion (see Ptolemaic system Ptolemaic system (tŏl'əmā`ĭk), historically the most influential of the geocentric cosmological theories, i.e.
..... Click the link for more information. ). Thus, the Copernican system was technically only a slight improvement over the Ptolemaic system. However, making the solar system heliocentric removed the largest epicycle and explained retrograde motion in a natural way. By liberating astronomy from a geocentric viewpoint, Copernicus paved the way for Kepler's laws Kepler's laws, three mathematical statements formulated by the German astronomer Johannes Kepler that accurately describe the revolutions of the planets around the sun. Kepler's laws opened the way for the development of celestial mechanics, i.e.
..... Click the link for more information. of planetary motion and Newton Newton, Sir Isaac, 1642–1727, English mathematician and natural philosopher (physicist), who is considered by many the greatest scientist that ever lived.
..... Click the link for more information. 's embracing theory of universal gravitation gravitation, the attractive force existing between any two particles of matter .

The Law of Universal Gravitation

Since the gravitational force is experienced by all matter in the universe, from the largest galaxies down to the smallest particles, it
..... Click the link for more information. , which describes the force that holds the planets in their orbits.

Bibliography

See E. Rosen, Copernicus and His Successors (1995); T. S. Kuhn, The Copernican Revolution (1997).

Copernican system

or Copernican principle

Model of the solar system centred on the Sun, with Earth and other planets revolving around it, formulated by Nicolaus Copernicus in the mid 16th century. Having the Sun in this central position explained the apparent motion of planets relative to the fixed stars and was truer than the Earth-centred Ptolemaic system (see Ptolemy). Scientifically, the Copernican system led to belief in a much larger universe than before (because, if the Earth revolved around the Sun, the stars would have to be very distant not to appear to alter their position); more broadly, the Copernican principle is invoked to argue against any theory that would give the solar system a special place in the universe. Dethronement of Earth from the centre of the universe caused profound shock: the Copernican system challenged the entire system of ancient authority and required a complete change in the philosophical conception of the universe.