Astro study guide

Astro study guide - Chapter 4 Aristotle- Believed that...

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Chapter 4 Aristotle - Believed that universe was made up of the changing, imperfect earth, and the perfect, immutable heavens. The heavens surrounded earth, and there were 55 crystalline spheres turning at different rates and angles. The moon marked the boundary of the earth and the heavens. Since the earth was immobile, the spheres moved westward around the earth. The earth was a sphere because it cast a round shadow during lunar eclipses. Aristarchus proposed a theory that the earth rotated on its axis and revolved around the sun. Eratosthenes found the radius of the earth using measurements and shadows. Hipparchus made the first star catalog, invented trigonometry, and discovered precession. He proposed that the sun and the moon traveled around circles with Earth near, but not at, their centers. Called eccentrics . Ptolemy created a mathematical model where the planets follow around a small circle called the epicycle that slides around a large circle called the deferent.
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Astro study guide - Chapter 4 Aristotle- Believed that...

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