ASTRON 1F03 Chapter Notes - Chapter 1: Deferent And Epicycle, Semi-Major And Semi-Minor Axes, Retrograde And Prograde Motion
25 Jul 2016
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Document Summary
Dif cult to describe in earth centred system - ptolemy. Epicycles were used - each planet had a different epicycle. Galilei, 1564-1642 - many key, telescopic, astronomical observations. Venus has phases - impossible to explain in geocentric model. In contradiction to general belief that the heaven were constant and immutable. Planetary orbits are ellipses, sun at one focus. An imaginary line connecting sun and planet sweeps out equal areas in equal times. Square of period of planet"s orbital motion is proportional to cube of semi-major axis. 1 au, earth to sun - calculated with venus and radar. Mass remains at rest or at a constant linear velocity unless a force acts on it. When a force is exerted on an object, a is proportional to 1/m, and, f = ma. When one body exerts a force on a second body, the second body simultaneously exerts a force equal in magnitude and opposite in direction on the rst body.
