The History and Philosophyof Astronomy (Lecture 6: Copernicus I)Instructor: Volker BrommTA: Amanda BauerThe University of Texas at AustinAstronomy 350L (Spring 2005)Astronomy during the Renaissance (c. 1450 – 1600)• Rebirth of cultural activity in Europe!Intellectual Climate: Reformation (1517 onwards)• Restore lost original (pure) state of Church! Martin LutherIntellectual Climate: Humanism • Anti-Aristotelian strain, desire for classics! Erasmus of RotterdamPico della MirandolaIntellectual Climate: Neoplatonism• Search for underlying (mathematical) structureof reality! Marsilio Ficino• mathematical harmony• Sun worshipIntellectual Climate: Voyages of DiscoveryColumbus(1451-1506)Spanish and Portuguese exploration• New spirit of discovery!Intellectual Climate: Fall of Constantinople 1453• Escape of Greek scholars and texts to Italy!Intellectual Climate: Invention of Printing Press• Rapid dissemination of knowledge!Johannes GutenbergNicolausCopernicus • 1473 – 1543• De RevolutionibusOrbium Coelestium(1543, On the Revolutionof the Heavenly Spheres)• What was he:- first modern astronomer?- last ancient astronomer?NicolausCopernicus: Geography of his LifeCopernicus: Studies in Italy Bologna• Bologna and Padua: astronomy, mathematics, medicine, law• Eventually: Doctorate in church law (Ferrara)PaduaCopernicus: Canon at FromborkCathedral • Q: What is a canon?Copernicus: War in Varmia (1519-1521) • Poland vs Teutonic Knights, Copernicus involved in defenceCopernicus: De Revolutionibus(1543) • heliocentric model• Q: What motivated him?• Q: Structure of book?• Q: In which way was itrevolutionary?De Revolutionibus: Basic Motivation • Q: What motivated him?• A: in preface• Against Ptolemaic“monster”!• Ptolemaic system ugly,arbitrary, and inaccurate(Pope Paul III)Basic Motivation: Need for better calendar (Pope Gregory XIII)De Revolutionibus: Basic Structure • Book 1: Popular justification for Earth’s motion• Book 2-6: Mathematical details to account forcelestial (planetary) motions• Book 1: not original, not really convincing• Book 2-6: highly specialized(“Mathematics is for mathematicians”)De Revolutionibus: Basic Principles (Book 1) • Sun-centered• Earth is planet (3rd from Sun)• Earth’s motions:- daily rotation- annual revolution around Sun• Celestial motions uniform and circular• finite universeDe Revolutionibus: Basic Principles (Book 1) • daily rotation of celestial (fixed star) sphere• yearly motionof Sun alongecliptic (zodiac)De Revolutionibus: Aesthetic Appeal PtolemyCopernicus• Conceptually simpler explanation for retrogrademotion (7 spheres vs 12)• Retrograde motion of planets natural outcome ofEarth’s motion!De Revolutionibus: Final Result (Books 2-6) PtolemyCopernicus• As messy as Ptolemy, not more accurate:- a failure really (according to original claim)Copernicus (part 1)• Transitional figure in history of astronomy!• Still deeply routed in ancient (Arsitotelian-Ptolemaic)tradition• But also: A typical Renaissance figure- daring to do things differently- Neoplatonic influence (from his time in Italy) • De Revolutionibus: Not a revolutionary book,but a revolution-making
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