9.7.07 Astronomy notes

9.7.07 Astronomy notes - -Sun at center-Earth rotates-Earth...

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Things in galaxy: Earth Sun & moon - Uniform west east motion Fixed stars Planets - Mercury, Venus, mars, Jupiter, Saturn - Retrograde motion - Brightness variations - Mercury and venus are always close to the sun Aristotle: 384 – 322 BC Geocentric model - Earth at center - Deferents - Epicycles o Epicycle attached to deferent. Deferent spins, so does epicycle o Epicycle moves slowly eastward along deferent o E rotates faster, accounts for retrograde - Measurements were close, but not perfect Ptolemy: 140 AD - Shifted circles. Deferent and epicycle centers offset - Still not perfect, but very close - Relatively unquestioned for 13 centuries Heliocentric model: - Aristarchus (310 – 230 BC) - Copernicus ( 1473 – 1543 AD)
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Unformatted text preview: -Sun at center-Earth rotates-Earth and planets revolve around sun, moon around earth-Naturally has retrograde motion and brightness variation-Measurements were worse than Ptolemy’s-He is missing elliptical orbits-Added epicycles back in with deferent centered on sun-Now slightly better than Ptolemy’s, no one cared o Written in Latin o Published posthumously with disclaimer from publisher o Violated the Church o Wasn’t banned for 73 years Galileo: 1564 – 1642 AD-Experimentalist -First to use a telescope to look at the sky-Four discoveries 1609 o Lunar features o Sun spots o Jovian moons o Venusian phases...
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