[PHYSICS 20A] - Final Exam Guide - Comprehensive Notes fot the exam (31 pages long!)
29 Mar 2017
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18 jan. 2017: why do planets shine, they reflect light from the sun. Planets can be brighter than most stars or as faint as the other stars depending on their size and distance. Inferior vs superior planets: inferior - whose orbit is interior to the earth"s orbit, lies along the ecliptic plane but always stays within a set max. Angular distance away from the sun: superior-whose orbit lies outside the earth"s orbit, can appear anywhere along the ecliptic plane. Wandering stars: they would keep track of time and seasons, but planet exhibit complex motion, including retrograde motion on the celestial sphere, ptolemy tried to save the geocentric model by adding epicycles. Heliocentric model: retrograde occurs bc the inner planets rotate faster than outer planets, happens whenever earth takes over. Let p be the period given in years: says: p^2 yr = a^3 au, consequences distant planets take longer to orbit the sun and travels at a slower speed.
