ASTRO-110 Lecture Notes - Lecture 20: Semi-Major And Semi-Minor Axes, The Moons, Sandford Fleming
18 Sep 2020
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Document Summary
Up to the time of galileo there was no actual proof that copernicus was correct and the solar system was heliocentric. Galileo supplied the most striking proof, with his observation, the new telescope that he invented, that the planet venus showed phases like the moon. There is one further great consequence of newton"s derivation of kepler"s laws from basic principles. Newton"s formulation of the third law, relating the semi-major axis of the orbit to the sidereal period, gave a formula that had only one unknown quantity - the mass of the sun. Using newton"s version of kepler"s third law, and knowing the distance of any one planet (say the earth) from the sun, we can calculate the mass of the sun! Because it has an object in orbit about it - the. Moon, and we can apply newton"s version of the third law to calculate the mass.
