2. What is it…? A Duck, or a Rabbit?!

4. Pythagoras: “All is Number”  the “Music of the Spheres” Intervals between harmonious musical notes always have whole number ratios. Playing half a length of a guitar string gives the same note as the open string, but an octave higher; a third of a length gives a different but harmonious note; etc. Non-whole number ratios, on the other hand, tend to give dissonant sounds. Pythagoras described the primary building blocks of musical harmony: the octave (1:1), the perfect fifth (3:2), the perfect fourth (4:3) and the major third (5:4). Pythagoras at his “Monochord”:

5. The “Geocentric Universe” of Pythagoras & Aristotle

6. So… If the “Dome of the Stars” turns the Universe, then what turns the Dome of the Stars…? Obviously, it’s the “Prime Mover”!

14. The Golden Age of Islamic Astronomy (825 – 1450 A.D.)

15. Nicolaus Copernicus (1473 – 1543 A.D.)

19. Giordano Bruno The monument to Bruno in the place he was executed, Campo de' Fiori in Rome. (1548 – 1600 A.D.) “It may be you fear more to deliver judgment upon me than I fear judgment.”

20. Galileo Galilei (1564 – 1642 A.D.)

21. Galileo's Sidereus Nuncius (the “Starry Messenger”), this edition from 1653. Galileo first described craters and mountains on the Moon, as seen with a telescope. Galileo Observed… Enormous Craters on the Moon

23. Galileo's sketch of a sky filled with stars. (A drawing of the Andromeda Galaxy… …Like the Milky Way!)

24. Galileo Observed… Four Large Moons of Jupiter

25. Galileo Observed… The Phases of Venus

26. The first successful measurements of Stellar Parallax (of 61 Cygni)… Friedrich Bessel’s “Heliometer” in 1838!

27. Tycho Brahe (1546 – 1601 A.D.) (and his Private Observatory, “Uraniborg”, on Hven Island)

28. Johannes Kepler (1571 – 1630 A.D.)

29. Kepler’s 1 st Law…

30. Kepler’s 1 st Law: Planetary Orbits are Ellipses with the Sun at 1 Focus

31. Kepler’s 2 nd Law…

32. Kepler’s 2 nd Law: Equal Areas are “Swept Out” in Equal Times

34. Isaac Newton (1642 – 1727 A.D.)

38. waowen.screaming.net/revision/force&motion/ncananim.htm “Newton’s Cannon” Animation:

43. Q: How to detect dim “Extrasolar Planets” (“Exoplanets”)? A: Use Newton’s Third Law! (“Action-Reaction”… i.e., “Force-Counterforce”)

47. Extrasolar Planets (“Exoplanets”) Web Link: The Extrasolar Planets Encyclopedia (http://exoplanet.eu)

48. “There is a single general space, a single vast immensity which we may freely call void: in it are innumerable globes like this on which we live and grow, this space we declare to be infinite, since neither reason, convenience, sense-perception nor nature assign to it a limit.” — Giordano Bruno Quoted in Joseph Silk, “The Big Bang” (1997) Giordano Bruno Habitable Exoplanets Catalog (http://phl.upr.edu/projects/habitable-exoplanets-catalog)