1. Kepler’s Laws of Planetary Motion
Guiding Questions
What are the shapes and important properties of the planetary orbits?
How does the speed of a planet vary as it orbits the sun?
How does the period of a planet's orbit depend on its distance from the Sun?

2. Kepler’s First Law – The Law of Ellipses
The orbits of the planets are elliptical (not circular) with the Sun at one focus of the ellipse

3. Eccentricity The shape of the ellipse
Distance between foci / length of the major axis

4. Kepler’s Second Law – The Law of Equal Areas
An imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time

5. As the planet is closest to the sun, the planet is moving fastest and as the planet is farthest from the sun, it is moving slowest

6. Kepler’s Third Law – The Law of Harmonies
Compares the orbital period and radius of orbit of a planet to those of other planets

7. The further the planet from the sun, the longer the period
Amount of time an object takes to make a full orbit

8. Conclusion
Kepler’s Laws provided a complete description of planetary motion (including the motion of planetary satellites, like the Moon)