PHYS 1600 Chapter Notes -Obits, Almagest, Ellipse
23 Mar 2013
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Cosmology: the study of the formation, organization and evolution of the earth. 2-2 the belief that in a sun-centered cosmology formed slowly: Direct motion: the gradual, eastward apparent motion of a planet against the background stars as seen from earth. Retrograde motion: the occasional backward (that is westward) apparent motion of a planet against the background stars as seen from earth. All planetary motions on the celestial sphere are much slower than the apparent daily movement of the entire sky caused by earth"s rotation. Ancient greek astronomer aristarchus of samsos proposed a more straightforward explanation of planetary motion, that the planets revolve around the sun. The retrograde motion of mars in a heliocentric cosmology occurs because faster moving earth over-takes and passes mars. Heliocentric is a misleading word: the sun and the bodies that orbit it all orbit the center of our. Gravitational force of the planets is held by the sun.
