1. Kepler’s Laws
Physics
Mrs. Coyle

2. Geocentric View Points
Aristotle (Greek) BC
Ptolemy (Alexandrian Greek) 85-65AD

3. Heliocentric Viewpoints
Aristarchus (Greek) BC
Copernicus (Poland and Italy)
Galileo Galilei (Italian)

4. Tycho Brahe (Danish) (Dec 14)1546-1601

5. Tycho Brahe (Danish)
Worked on the Island of Hven near Copenhagen at the Uraniborg Observatory
Compromise Theory: The Sun orbits the Earth, but the remaining planets orbit the Sun.
Btrahe passed along his observations to Johannes Kepler, his assistant.

6. Brahe’s Compromise Theory

8. Johannes Kepler
( ) German Astronomer

9. Kepler’s First Law (Law of Orbits):
Planets move in elliptical orbits with the Sun at one of the focal points.
E L L I P S E

10. Kepler’s Laws Animation

11. Kepler’s 2nd Law(The Law of Areas)
A line from the sun to a planet sweeps out equal areas in equal lengths of time.

12. Where is the speed of the earth greater, point B or C?

13. Kepler’s Laws Animation

14. Kepler’s Third Law ( Law of Periods or Law of Harmony)
The square of the orbital period of a planet is directly proportional to the cube of the average distance of the planet from the Sun.
K for our Solar System

15. Kepler’s Third Law ( Law of Periods or Law of Harmony)
2 3 ( _ Ta___ ) = ( _ ra ___ ) Tb rb

16. EXAMPLE:
An asteroid revolves around the sun with a mean orbital radius of three times that of the earth. What is the period of the asteroid in earth years?
Answer: 5.2y

17. Video -9 Min