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A Short History of Astronomy. Ancient (before 500 BC) Egyptians, Babylonians, Mayans, Incas, Chinese Classical Antiquity (500 BC-500 AD) Greeks, Romans: Plato, Aristotle, Ptolemy Middle Ages (500-1450 AD) Arabic astronomers Renaissance (1450-1550 AD)
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A Short History of Astronomy • Ancient (before 500 BC) • Egyptians, Babylonians, Mayans, Incas, Chinese • Classical Antiquity (500 BC-500 AD) • Greeks, Romans: Plato, Aristotle, Ptolemy • Middle Ages (500-1450 AD) • Arabic astronomers • Renaissance (1450-1550 AD) • Copernicus • Baroque (1550-1700 AD) • Brahe, Kepler, Galilei, Newton
Ancient Astronomy Stonehenge, England Pyramids, Gizeh near Cairo, Egypt
“Strange” motion of the Planets Planets usually move from W to E relative to the stars, but sometimes strangely turn around in a loop, the so called retrograde motion. (Explanation: next lecture!)
Ptolemy (~140 AD) • Puts forth a complete geocentric model • dominates scientific thought during the Middle Ages • Longest lasting (wrong) theory ever: 1000yrs Major Work:Almagest
Epicycles • Ptolemy’s explanation of retrograde motion • About 40(!) epicycles necessary to explain all observations complicated theory
Nicolas Copernicus (1473–1543) • Rediscovers the heliocentric model of Aristarchus BOOKS! • Planets on circles • needs 48(!!) epicycles to explain different speeds of planets • Not more accurate than Ptolemy Major Work :De Revolutionibus Orbium Celestium (published posthumously)