PHYSICS 20B Study Guide - Midterm Guide: Semi-Major And Semi-Minor Axes, Big Bang, Ellipse
21 Jul 2016
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Lec 1: age and physical scale of solar system, galaxy, universe. 100,000 yrs to cross milky way and 2. 5 million yrs to reach next galaxy. Arstarchus said since sun is larger, it must be at the center. Ptolemy basically wrong about everything while copernicus was right. Brahe discovered a supernova which had to be very distant instead of in earth"s realm. Galileo discovered moons of jupiter > not everything revolved around earth; phases of venus were only possible in heliocentric model. Law 1: ellipse rather than circle with sun at one of the focuses. Law 2: a line that connects a planet to the sun sweeps out equal area in equal time. Law 3: square of the period is prop. to cube of the semi-major axis(radius on major axis) of its orbit. Law of gravity: all objects attract to one another, gravity is greater from larger objects, gravity is smaller from something far away.
