ASTRO-110 Lecture Notes - Lecture 6: Nicolaus Copernicus, Retrograde And Prograde Motion, Geocentric Model
18 Sep 2020
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Document Summary
Planets orbit on small circles whose centers orbit the earth on larger circles (epicycles) Thought ptolemy"s model was contrived, but he believed in circular motion. Sun is at center heliocentric model. Retrograde motion occurs when we lap other planets. Johannes kepler (1571-1630) & tycho brahe (1546-1601) Each planet"s orbit around the sun is an ellipse, with the sun at one focus. A planets moves along its orbit with a speed that changes in such a way that a line from the planet to the sun sweeps out equal areas in equal intervals of time. The ration of the cube of a planet"s average distance from the sun to the square of its orbital period is the same for each planet. A = distance from sun in au. P = period of orbit around sun in years. First man to point a telescope at the sky. Dialogue of concerning the two chief world systems. Got him in trouble with the church.
