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Both models have the Sun in the centre and all the planets going round it, including the Earth.
Copernicus (1543) used a system of circles and epicycles similar to the one used by Ptolemy over a thousand years earlier. Both models represented the movements of the planets among the stars with quite good accuracy.
Kepler (1609) used the novel idea of elliptical orbits for the planets. Tycho Brahe had made new observations with unprecedented accuracy, and Kepler found that the new elliptical model fitted these observations more accurately than the other models.
At the time the new model was published there was no way of deciding which model was right. But, 70-80 years later, Isaac newton's theoretical discoveries in gravity and dynamics were used to show that the planets must follow elliptical orbits under the force of the Sun's gravity. After that Kepler's model was accepted generally.
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What changes Kepler had to made in order to fit the observations of Tycho Brahe into the heliocentric system of Copernicus?
Kepler had to modify the Copernican system by proposing that planetary orbits were elliptical, not circular as Copernicus had assumed. This change helped to better match Tycho Brahe's detailed observational data on the planets' positions. Kepler's new model became known as Kepler's laws of planetary motion.
Who proved the accuracy of Copernicus ideas about motion of planets?
Johannes Kepler was the one who provided the evidence and mathematical framework to support Copernicus' heliocentric model of the solar system through his laws of planetary motion.
What is the similarity between the Ptolemy and Copernicus models of the solar system?
The similarity is that both theories used a system of circles and epicycles to explain how the planets move around. Copernicus's theory (1543) used a similar number of epicycles, but many of them were smaller so that the paths followed by the planets were geometrically simpler. The difference was that Copernicus placed the Sun at the centre rather than the Earth as the ancient theory had done. Another theory was later produced by Kepler (1609), which used Copernicus's idea of having the Sun at the centre, but Kepler used elliptical orbits for the planets. This new model fitted observational measurements better, but it was not until many years later after the discovery of the law of gravity and the laws of motion (1687) that it was possible to pick out Kepler's theory as the correct one that is still in use today.
What is the main difference between Kepler's system and the Copernicus system?
Both systems have the Sun at the centre, but Copernicus stuck to the ancient model of circles and epicycles to explain the planets' orbits. Kepler on the other hand used new measurements by Tycho Brahe to suggest, after a lot of detailed calculations, that the planets move in elliptical orbits. The difference between an ellipse and a circular orbit with an epicycle is extremely small in the case of planetary orbits which have a low eccentricity factor. It was not until Tycho came along that measurements of sufficient accuracy were available for Kepler to make his discovery. Later the elliptical orbits were explained theoretically, after the discovery of the law of gravity and the laws of motion. This eventually led to Kepler's theory being generally accepted as right, which it still is.
What do Copernicus Galileo kapler and newton have in common?
Galileo did not have his own theory. He was a supporter of Copernicus's heliocentric theory and an opponent of the geocentric Ptolemaic theory. Eventually both theories were rejected in favour of Kepler's theory. But Kepler's theory uses the heliocentric idea from Copernicus's theory.
