Think About It: For 1,700 years what did we believe about the Earth and the Sun and their motions? Why did we believe that? For 1,700 years what did we believe about the Earth and the Sun and their motions? Why did we believe that?

Aim: How do we prove the earth rotates and revolves? Topic: Unit 8 Astronomy Topic: Unit 8 Astronomy Main Idea: Heliocentric and Geocentric Views Main Idea: Heliocentric and Geocentric Views

1) What does the word “geocentric” mean? “earth-centered”; this is the view that the earth is the center of the universe. “earth-centered”; this is the view that the earth is the center of the universe.

What was the “heliocentric view”? This was the view that the earth and planets revolved around the sun. This was the view that the earth and planets revolved around the sun.

2) Why do planets look like they are moving backward at certain points? At times in our orbit around the sun, we move faster so another planet looks like it’s going backward. At times in our orbit around the sun, we move faster so another planet looks like it’s going backward.

3) What are the two terrestrial motions? Rotation= the counterclockwise spinning on an axis at a rate of 15 degrees per hour Rotation= the counterclockwise spinning on an axis at a rate of 15 degrees per hour Revolution= one object going around another (earth revolves counterclockwise at a rate of 1 degree per day) Revolution= one object going around another (earth revolves counterclockwise at a rate of 1 degree per day)

Why were the pegs knocked down by the Foucault pendulum? The earth rotated under them; fastest at the equator and slowest at the poles. The earth rotated under them; fastest at the equator and slowest at the poles.

Proof of Rotation

Proof of Revolution

Evidence Rotation Day and night Coriolis effect Foucault pendulum Revolutionseasons Changing constellations

Exit Card Use tonight’s homework questions 1, 5, 7 & 10