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Great Discoveries In Astronomy

Explore the fascinating ancient views on the universe by prominent philosophers such as Pythagoras, Philolaus, and Aristotle.

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Great Discoveries In Astronomy

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  1. Great Discoveries In Astronomy April 1, 2005 (c) 2005 Christopher Carosa

  2. Why ASTRONOMY? ? ! ? ? ! ? (c) 2005 Christopher Carosa

  3. Why ASTRONOMY? The Significance of It All • It’s Everywhere • It Seems Important • Raises Questions • Suggests Conclusions (c) 2005 Christopher Carosa

  4. Why ASTRONOMY? Means of Measurement • Passage of Time • Course of a Voyage • Our Position in the Universe • Our Power of Knowing (c) 2005 Christopher Carosa

  5. Why ASTRONOMY? Philosophical Beginnings • Who are we? • What are we? • Where are we? • Why are we? (c) 2005 Christopher Carosa

  6. Why ASTRONOMY? The Eyes Have It “God invented and gave us sight to the end that we might behold the courses of intelligence in heaven, and apply them...” • Plato (c428-c347BC),Timeaeus (c) 2005 Christopher Carosa

  7. Why ASTRONOMY? If You Wanna Be Smart… “He who has not contemplated the kind of nature which is said to exist in stars... is not able to give a reason for such things to have reason.” • Plato (c428-c347BC),Laws (c) 2005 Christopher Carosa

  8. Why ASTRONOMY? Intellectual Prerequisite • Ancient philosophers felt the study of ASTRONOMY was required for intellectual thinking - true life, in their definition. (c) 2005 Christopher Carosa

  9. Why ASTRONOMY? Spiritual Prerequisite • They also attributed an intelligence, or life, to celestial bodies, both as a way to justify the pursuit of ASTRONOMICAL knowledge in the religious sense and explain the then unexplainable. (c) 2005 Christopher Carosa

  10. Why ASTRONOMY? The Seven Liberal Arts • Grammar • Logic • Rhetoric • Arithmetic • Geometry • ASTRONOMY • Music (c) 2005 Christopher Carosa

  11. Ancient Cosmologies (c) 2005 Christopher Carosa

  12. Ancient Cosmologies Anaximander (c611-c547BC) • First known attempt to model universe (c555BC). • Earth was a cylinder. • Stars were rings of fire. • Radical, dude. (c) 2005 Christopher Carosa

  13. Anaximander’s Universe • The cylinder containing the Sun • The Moon’s cylinder • Each star also had its own cylinder • Earth is a cylinder 1 unit high and 3 units wide, with the top and bottom faces inhabited. • The Sun, the Moon and each of the stars is actually a hoop – or cylinder – made of air (so it is transparent). • Each hoop is filled with fire which we can only see when the hole in that particular hoop passes over us. • Eclipses are blockages in the holes. (c) 2005 Christopher Carosa

  14. Ancient Cosmologies Pythagoras (c569-c480BC) • Yes, that guy, who also figured out the “morning star” and the “evening star” were both Venus. • Heavenly objects are spherical. • Objects move in perfect circles. • “Music of the Spheres.” (c) 2005 Christopher Carosa

  15. Pythagoras’ Universe (c) 2005 Christopher Carosa

  16. Ancient Cosmologies Philolaus (c450BC) • A follower of Pythagoras. • First to say the Earth moved. • Objects moved around a central fire. • “Antichon” – the 10th sphere. (c) 2005 Christopher Carosa

  17. Philolaus’ Universe Moon Wandering Stars (Planets) Sun Fixed Stars (“Celestial Sphere”) Earth Antichon Central fire - hearth of the Gods (c) 2005 Christopher Carosa

  18. Ancient Cosmologies Empedocles (c490-430BC) • Also a follower of Pythagoras. • Refused crown of Agrigentum. • Thought the stars were made of fire, but not the Sun. • Thought the moon was made of air that reflected light. (c) 2005 Christopher Carosa

  19. Empedocles’ Universe (c) 2005 Christopher Carosa

  20. Ancient Cosmologies Anaxarogas (c500-428BC) • May have taught Socrates. • Studied meteorites. • Believed everything was made of the same stuff as Earth. • Thought the Sun was a red-hot stone. (c) 2005 Christopher Carosa

  21. Ancient Cosmologies Eudoxus (c408-355BC) • Discovered 1 year = 365 ¼ days. • Explained motion using rotating spheres. • Thought stars were on a fixed sphere rotating separately. • “Saved the phenomena.” (c) 2005 Christopher Carosa

  22. Ancient Cosmologies Aristotle (384-322BC) • A student of Plato. • Taught Alexander the Great. • His works have influenced nearly every modern subject. • Believed observation was crucial to all things. (c) 2005 Christopher Carosa

  23. Ancient Cosmologies Fire Aristotle’s Observations Air Water Dirt (c) 2005 Christopher Carosa

  24. Ancient Cosmologies Aristotle Types of Matter Corruptible Matter • Can be created and destroyed. • Exists on Earth. • Moves in straight lines (which are not perfect). Incorruptible Matter • Can be neither created nor destroyed. • Exists in the Heavens. • Moves in circles (which are perfect). (c) 2005 Christopher Carosa

  25. Ancient Cosmologies Aristotle – the Earth is round • Earth’s shadow during a lunar eclipse. • Northbound and southbound travelers see different stars. • You see elephants in India and Morocco, so those two places must be close together! (c) 2005 Christopher Carosa

  26. Ancient Cosmologies Aristotle Cosmology • Explained apparent motion could be explained either way. • Rejected heliocentric theory because he observed no parallax. • Ideas similar to Eudoxus, but believed his theory actually described real world. (c) 2005 Christopher Carosa

  27. Aristotle’s Universe (c) 2005 Christopher Carosa

  28. Ancient Cosmologies Aristarchus (c310-c250BC) • First to propose the Earth revolved around the Sun. • Developed correct methodology for measuring relative distances of the Sun and the Moon from Earth. • Right idea, but wrong results. (c) 2005 Christopher Carosa

  29. Ancient Cosmologies A Slight Problem (c) 2005 Christopher Carosa

  30. Ancient Cosmologies Ptolemy (c100AD-170) • Solved retrograde motion. • Conforms to what we see. • Still in use today for navigational purposes. • “Saved the appearances.” (c) 2005 Christopher Carosa

  31. Ptolemy’s Universe (c) 2005 Christopher Carosa

  32. Medieval Astronomy Summary • The circle (or sphere) is perfect. • Heavenly bodies don’t change. • Aristotle’s physics. • Ptolemy’s model. (c) 2005 Christopher Carosa

  33. Medieval Astronomy Oops, they did it again! (c) 2005 Christopher Carosa

  34. Medieval Astronomy Discontent with Ptolemy • Understated precession value. • Trepidation was falling apart. • Growing philosophical dissent. • By 1500, time for a change. (c) 2005 Christopher Carosa

  35. The Copernican Revolution Nicolaus Copernicus (1473-1543) • Not known for his observations. • He analyzed the work of others. • Astronomy was a hobby. • Papal consultant on calendar reform. (c) 2005 Christopher Carosa

  36. The Copernican Revolution Copernicus’ De Revolutionibus • De Revolutionibus Orbium Coelestium. • Explained 1,000s of observations. • Made 1,000s of comparison predictions vs. Ptolemy. (c) 2005 Christopher Carosa

  37. Copernicus’ Universe (c) 2005 Christopher Carosa

  38. The Copernican Revolution Copernicus’ De Revolutionibus • Correctly ordered and sized the Solar System. • Did not prove the Earth went around the Sun. • Published shortly before his death. (c) 2005 Christopher Carosa

  39. The Copernican Revolution Copernicus’ Controversy • Banned by both Protestants and Catholics. • Giordano Bruno burned at the stake for supporting it. • Return of “saving for appearances.” (c) 2005 Christopher Carosa

  40. The Copernican Revolution Ramifications of Copernicus • Did not improve on Ptolemy. • He died believing its truth. • He didn’t have the evidence to prove the truth of the theory. • Demoted the status of the Earth to an ordinary planet. (c) 2005 Christopher Carosa

  41. The Copernican Revolution Ramifications of Copernicus • Revolutionized science. • Profoundly altered man’s perception of himself. • First to describe the precession of the Equinoxes (but not why). • Incorrectly used circular motion. (c) 2005 Christopher Carosa

  42. The Copernican Revolution Tycho Brahe (1546-1601) • Best pre-telescopic observer. • Discovered 1572 nova. • Proved comets travel between planets. • Tried to advance an alternative to Copernican system. (c) 2005 Christopher Carosa

  43. The Copernican Revolution Johannes Kepler (1571-1630) • Observed 1606 nova. • Provided empirical support. • Discovered laws of motion. • Concluded planets had elliptical orbits. (c) 2005 Christopher Carosa

  44. Kepler’s Universe (c) 2005 Christopher Carosa

  45. The Copernican Revolution Galileo Galilei (1564-1642) • Nicknamed the “Wrangler.” • Advanced a new physics. • Among the first to use the telescope for astronomy. • His observational discoveries sealed the fate of Aristotle et al. (c) 2005 Christopher Carosa

  46. Galileo’s Universe (Part I) (c) 2005 Christopher Carosa

  47. Galileo’s Universe (Part II) (c) 2005 Christopher Carosa

  48. Galileo’s Universe (Part III) (c) 2005 Christopher Carosa

  49. Galileo’s Universe (Part IV) (c) 2005 Christopher Carosa

  50. The Copernican Revolution Galileo Goes Public • Began to publicly support the Copernican system. • Asked by the pope to renounce his position. • He complied. (c) 2005 Christopher Carosa

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