PHYS 1901 Lecture Notes - Lecture 4: Deferent And Epicycle, Sidereal Time, Heliocentrism
10 Dec 2015
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Universe: about 13. 7 billion years old, light travels 300. 000 km/s, therefore sun is 8 light minutes away, it is smooth and made with uniform ingredients, elements on the periodic table, dark matter=things unknown/not on the periodic table. Sidereal day = time it takes for the sun to get from directly overhead to the same position: 23 hours 56 minutes, different than 24 hour day because sun travels along the ecliptic. Analemma = sun traveling along the ecliptic in the sky, looking like a gure. 8: the line of best t for this gure 8 gives us the 24 hour clock. Angles and measurement: ancient greeks, eratosthenes, determine the earth size, circumference of a circle 2 r, 360 , alexandria-syene diagram . Moon moves on its own path, relative to the ecliptic. It takes 27 days to do a full rotation.
