1. MODELS OF THE SOLAR SYSTEM Chap. 29, Sect. 1 OBJECTIVES: SWBAT… 1. Compare the models of the universe developed by Ptolemy and Copernicus. 2. Summarize Kepler’s 3 laws of planetary motion.

2. EARLY VIEWS OF SOLAR SYSTEM 1. Earth is center: geocentric theory. (Aristotle) 2. Earth is flat and motionless.

3. GEOCENTRIC THEORY

4. EARLY VIEWS OF SOLAR SYSTEM 3. Greeks: planets move in reverse direction (retrograde motion).

5. RETROGRADE MOTION

6. CLAUDIUS PTOLEMY

7. EARLY VIEWS OF SOLAR SYSTEM 4. Ptolemy: “planet has 2 motions”: A. one is around the Earth. B. one is on a smaller circle (epicycle).

8. EARLY VIEWS OF SOLAR SYSTEM C. explains retrograde motion.

9. EPICYCLES

10. NICHOLAS COPERNICUS

11. RISE OF MODERN ASTRONOMY 1. Copernicus: A. “sun is the center” B. “planets move at a different speed and direction, which explains retrograde motion.

12. COPERNICAN VIEW

13. TYCHO BRAHE

14. RISE OF MODERN ASTRONOMY 2. Tycho Brahe: A. uses 1 st pretelescopic instruments. B. charts over 700 stars in precise positions.

15. JOHANNES KEPLER

16. RISE OF MODERN ASTRONOMY 3. Johannes Kepler: A. analyzes Brahe’s data. B. comes up with 3 Laws of Planetary Motion.

17. RISE OF MODERN ASTRONOMY LAW 1: “The motion of a planet around the sun is an ellipse (oval-shaped).” A. sun occupies 1 foci. B. perihelion and aphelion.

18. LAW OF ELLIPSES

20. RISE OF MODERN ASTRONOMY LAW 2 (Equal Areas): “A line drawn from a planet to the sun sweeps out equal areas in equal amounts of time.”

21. LAW OF EQUAL AREAS

22. RISE OF MODERN ASTRONOMY LAW 3 ( Law of Harmony): “The cube of the ave. dist. Of a planet from the sun is always proportional to the square of the period.” K x r 3 = p 2

23. NEWTON’S LAWS Said that a moving body will change its motion only if an outside force causes it to do so. Inertia: the tendency of a moving body to move in a straight line at a constant speed until an outside force is applied.