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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. CopernicusCopernicus, Nicholas
, Pol. Mikotaj Kopérnik, 1473–1543, Polish astronomer. After studying astronomy at the Univ. of Kraków, he spent a number of years in Italy studying various subjects, including medicine and canon law. He lectured c.
..... 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 PtolemyPtolemy
(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 systemPtolemaic system
, historically the most influential of the geocentric cosmological theories, i.e., theories that placed the earth motionless at the center of the universe with all celestial bodies revolving around it (see cosmology).
..... 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 lawsKepler'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 NewtonNewton, Sir Isaac,
1642–1727, English mathematician and natural philosopher (physicist), who is considered by many the greatest scientist that ever lived. Early Life and Work
..... Click the link for more information. 's embracing theory of universal gravitationgravitation,
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 is often called
..... Click the link for more information. , which describes the force that holds the planets in their orbits.
See E. Rosen, Copernicus and His Successors (1995); T. S. Kuhn, The Copernican Revolution (1997).
Copernican system(kŏ-per -nă-kăn) A heliocentric system of the Solar System that was proposed by Nicolaus Copernicus and eventually published in 1543 in his book De Revolutionibus . It uses some of the basic ideas of the Ptolemaic system, including circular orbits and epicycles, and was no more accurate in its predictions. Copernicus, however, maintained that the planets move around the Sun (in the relative positions accepted today), the Sun's position being offset from the center of the orbits. The apparent motions of celestial bodies such as the Sun were explained in terms of the rotation of the Earth about its axis and also the Earth's orbital motion.
The planetary motion can be represented by two uniform circular motions: one is an epicyclic motion of the planet about a point D on the circular orbit; the other, unlike that of the Ptolemaic system, is a uniform circular motion of D about the center, C, of the orbit. This requires that the rate of motion of D about C is exactly half that of the epicyclic rate of motion with respect to a fixed direction.
There was a strong and prolonged reaction – especially by the Church – to the Copernican system, which effectively displaced the Earth as the center of the Universe. There was also a sudden revival in astronomical observation in order to test the theory, notably by Tycho Brahe. Tycho's detailed observations, which showed the inadequacies of the Copernican system, were used in the formulation of Kepler's laws of planetary motion. The heliocentric cosmology became firmly established after Galileo had made telescopic observations of the phases of Venus.