2. Sec. 26.2 pg.577-579 Solar System Models GEOCENTRIC ModelsHELIOCENTRIC Models Ancient Greeks Europeans Aristotle Ptolemy Copernicus Galileo Newton Tycho Kepler Brahe

4. Aristotle (350 B.C.) Greek Formulated a picture of the solar system that put Earth at its center with all the other heavenly bodies orbiting around it. GEOCENTRIC model The orbits were described as perfect circles.

5. The retrograde (backward, looping) motion of Mars. A composite image created by superimposing images taken on twenty-nine different dates.

6. The “Wanderers” The Greeks continued to watch the night sky, The Sun, moon, stars moved predictable orbit in the sky. BUT, there were five “objects” that did not follow this regular, predictable motion Once every year, they’d move BACKWARDS (retrograde) for a month or two!! They “wandered”, thus called planetes (Mercury, Venus, Mars, Jupiter Saturn)

7. PHENOMENON: What did you observe? What evidence do you have? OBJECTS : Define the system. What objects are interacting? MOTION: Describe the motion that in the model that explains your observations MODEL: Diagram of the model that Describes the motion and observations (evidence) Unit: _____________ Topic: __________________________

8. Observations http://www.davidcolarusso.com/astro/ Watch the animation and make observations about the motions of the planets and the Sun on your handout

9. To be continued…. http://www.youtube.com/watch?v=utH- GHH1FT8&feature=related http://www.youtube.com/watch?v=utH- GHH1FT8&feature=related Ptolemy http://www.youtube.com/watch?v=GevV1yvMJbc History Channel

10. Ptolemy (Greek) A.D. 140 Attempted to make a MODEL of the solar system that explained the motions of the planets you just observed! The model had to be testable by predicting future motion of the planets What does Ptolemy’s model look like? Then construct a model to explain the observed motion of the planets

11. Ptolemy’s model of the Solar System/Universe Epicycle

12. To be continued….