ASTRON 1101 Lecture Notes - Lecture 5: Mercedes-Benz Superdome, Deferent And Epicycle, Circular Motion

• School: Ohio State University
• Department: Astronomy
• Course: ASTRON 1101
• Professor: Barbara Ryden

Document Summary

First model of the universe: stars are lights attached to a solid, dome-like sky over a flat earth. The superdome model of the universe was common among early civilizations (egyptian, babylonian, early greek) Aristotle (4th century bce): first to give reasons why the earth is spherical. His most convincing reason came from lunar eclipses: during a lunar eclipse, earth"s shadow is always circular, the only object whose shadow is always circular is a sphere. Eratosthenes (200 bce), head of the famous library of alexandria; was the first to find the size of the earth. What eratosthenes read: at noon on june 21, the sun is at the zenith seen from syene. What he saw: the sun in 7. 2o south of the zenith seen from alexandria. What he assumed: the earth is spherical; the sun is very far away. Circumference = 50x distance from alexandria to syene. Distance from alexandria to syene = 5000 stades.