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Unformatted text preview: Sun and three extra spheres for each planet for retrograde motion. Total of 27 spheres. • Aristotle (384-322 BC) postulated gravity and physical laws of motion • Aristotle’s Cosmology: Two worlds: heavenly “ether” and sub-lunar “Earth, Water, Air and Fire”. Introduced 56-sphere geocentric model but still in error. He couldn’t explain variation in Moon’s size and variation in planet’s brightness but his model that Earth is in the center of the Universe stood for 2000 years. After Aristotle, the models became more quantitative. • Eratosthenes (300 BC): measures size of Earth to 1% accuracy....
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- Fall '11
- Physics, Earth-centered Geocentric