1. Geocentric vs. Heliocentric Models
Aim: How does the Earth move?

2. I. Two Models of Earth’s Motion
Geocentric Model- the belief that the universe revolved around the Earth.
Problems with this Theory- this idea couldn’t explain some natural phenomena

3. a. Coriolis Effect
Objects in the northern hemisphere are deflected to the right and objects in the southern hemisphere are deflected to the left.
Proof of rotation

4. b. Retrograde Motion of Planets
Planets, such as Mars, appear to move forward and backwards in the sky due to the fact that they are revolving around the sun at a slower rate than the Earth.
Proof of Revolution

6. c. Foucault Pendulum
After 24 hours, a free swinging pendulum will knock down 24 pins arranged in a circle. This occurs at a rate of 1 pin per hour, because the Earth’s rotation.
The BEST proof that the Earth is Rotating

8. A real Foucault Pendulum

9. D. Constellations
Different constellations can be viewed at different times throughout the year.
Proof of revolution

10. B. Heliocentric Model
The correct model, in this model the sun is in the center of our solar system.

11. Heliocentric Model Continued…
The heliocentric model includes two motions of planet Earth
Rotation- spinning on a daily basis, 15o/hr, 360o/day
2. Revolution- annual motion of the Earth orbiting the sun, 1o/day, 360o/year