Nicolaus Copernicus

1. Nicolaus Copernicus Born 1473 Torun, Poland Died 1543 Frauenburg, Poland

3. Background and education • Wealthy family • Started education at University of Krakow • moved to University of Bologna, Italy • studied canon law • moved to University of Padua, Italy • studied medicine • moved to University of Ferrara • studied canon law - doctorate 1503

4. Career • Taught mathematics in Rome • became canon at the University of Frauenburg – this position supported his astronomical studies • these date from Bologna • roomed with an astronomer, Novara, who was the official astrologer for the city • exposed to criticism of astrology and Ptolemy

5. Background • At this time - mathematics, astronomy and astrology were intimately associated • problems with Ptolemy were that the order of the planets was indeterminate (Venus and Mercury) • Structure of the zodiac was in question • Copernicus tried other ways of arranging things

6. Heliocentric system • Fixed Sun at center of circular orbits for all the planets - including Earth • All planets move at constant velocity along these circular orbits • order of things was: Mercury, Venus, Earth, Mars, Jupiter, Saturn • Earth was just another planet

7. Successes • Explained the difference between the inferior and superior planets • allowed the determination of the period for each planet • allowed the determination of the distance of each planet from the Sun

8. Results • . PeriodDistance • Mercury 88 days 0.39 AU • Venus 7.5 mo. 0.72 • Earth 1 year 1 • Mars 2yrs 2mo 1.6 • Jupiter 11.9 yrs. 5.2 • Saturn 29.6 yrs. 9.5

9. Results cont. • In other words, the distance and period give the same order of the planets in the solar system • simple explanation of retrograde motion - see the website following • http://csep10.phys.utk.edu/astr161/lect/ retrograde/copernican.html

10. Remaining errors • Circular orbits • Constant velocity

11. Publications • 1503 wrote the “Little Commentary” but did not publish it. • Visited by Georg Rheticus, mathematician, who was impressed by the heliocentric view • Urged Copernicus to publish the book, undertook to do this • No unpleasant response to this

12. Role of Osiander • This encouraged Copernicus to publish a larger work “On the revolutions of the heavenly spheres” • Rheticus moves and cannot proceed with the new book • Along comes Andreas Osiander, experienced with publishing technical books

13. Osiander • Takes on the task of publishing De Revolutionibus… • inserts a “letter to the reader” before the text saying that a) ideas presented did not represent truth, b) it was impossible to know the causes of heavenly phenomena • book appears in 1543 just as Copernicus dies

15. Major Conflict • Geocentric versus heliocentric • Extremely different views of the world • But no clear way to decide which is true • Needed more accurate observations of the planets • Also needed improvements in Copernican view

16. Interplay of theory and obs. • Theory due to Copernicus • Better (more accurate) observations need new observing tools • Along came Tycho Brahe • More accurate observations spur improvements in the theory • Along come Kepler and Newton

17. Old technology • Hand held instruments • made of wood • small and non-standard instruments

18. Astronomical and civil uses

19. Brahe • Danish nobility, wealthy, fascinated by astronomy (a precursor of Percival Lowell) • interested also in alchemy • lost part of his nose in a duel - gold replacement • was given an island by the Danish king, Hven, near Copenhagen for an observatory

20. Brahe • He represents a new kind of scientist, a professional who did “big science” • 1546-1601 • A transitional figure - between the apex of naked eye observations and the telescope (1608)

22. Astronomical observations • Observed the nova of 1572 - supposed to be a terrestrial phenomenon • Brahe showed the nova was far away (parallax) • Aristotle said it (nova) could not exist

23. Astronomical observations • Jupiter passes Saturn • predictions were off by days to months • Comet of 1577 • Aristotle said comets were terrestrial phenomena (in the atmosphere) • Brahe showed that the comet was placed among the planets (parallax)

25. Island of Hven

26. www.hven.com/EUBORG.htmlwww.hven.com/ELKRKART.html .

28. Brahe’s observatory on the island of Hven as it is today.

31. View of scale on the great mural quadrant

32. Brahe’s improvements • Metal instruments • fixed and therefore more stable • large and therefore more accurate • built a complete laboratory with printing shop, fabrication shops, assistants • continuous observations (vital) • corrected for refraction • also proposed a cosmological theory

34. Observations • Normally, observations of a planet were only made at a few positions in its orbit • Brahe had observations made continuously each clear night

36. Tychonic system

37. Brahe’s weaknesses • Strong on observation • weak on mathematics and theory • enlisted the help of Kepler in 1600 at Prague • at his death (1601), Brahe left his observations to Kepler • Kepler published the best planetary positions (Rudolphine tables)

38. Johannes Kepler • Born 1571 • Died 1630 • he was convinced that the universe was designed according to geometrical principles (God was a geometer) • trained as a mathematician • imperial mathematician to Rudolf II

39. Challenge • Calculated the positions of the planets and compared with Brahe’s observation • Worst agreement was for Mars • He spent 4 years trying to explain the orbit of Mars

42. Geometry aspect • Kepler asked the question “why are there only 6 planets”? • Answer: there are 5 platonic solids • cube, octahedron, tetrahedron, dodecahedron, and icosahedron • he used these solids to position the planets about the sun

43. Platonic solids • Cube - 6 faces -- earth • tetrahedron - 4 faces -- fire • octahedron - 8 faces -- air • dodecahedron - 12 faces -- aether • icosahedron - 20 faces --water

44. Cube

45. Tetrahedron

46. Octahedron

47. Dodecahedron

48. Icosahedron

49. Scheme • Pick a solid (for example, the cube) • start with a large sphere, solid inside touching the sphere • place another sphere inside the solid so that the sphere touches the solid • the planet moves in a circular orbit defined by the sphere • then, place another solid inside the sphere so that its corners touch the sphere