1. Background of Early Astronomers
Looking Back

2. A. Ptolemy (87-150 AD) He thought
1. Earth was the center of the solar system which is called a Geocentric view.
2. Other planets revolved around Earth, and as they did they also revolved around a central point.

3. A. Ptolemy ( AD)

4. A. Ptolemy

5. B. Copernicus (1473-1543) He thought:
1. Sun is center of the solar system & Earth revolves around it which is called the Heliocentric view (sun-centered).
2. All orbits are perfectly circular.
3. Earth rotates.
4. Earth’s axis is tilted.
5. Known as the founder of modern astronomy.

6. B. Copernicus ( )

7. B. Copernicus

8. C. Brahe ( )
He thought:
1. Earth is the center of the solar system, so the Sun revolves around it.
2. However, all other planets revolve around the Sun.
3. This is a Geo-Heliocentric view.
4. He tried to merge Ptolomy & Copernicus’
ideas.

9. C. Brahe ( )

10. C. Brahe

11. D. Kepler ( )
1. An assistant to Brahe, but once he died, he used his data and recalculated to get the correct description
2. He found:
a. All Planets do revolve around the Sun
b. Their orbits are elliptical

12. D. Kepler ( )

13. D. Kepler

14. E. Galileo ( )
1. Used the 1st telescopes to view the night sky in 1610.
2. He found:
a. Jupiter had 4 moons revolving around it, so Earth could not be the center of the universe.
b. Saturn’s rings, sunspots
3. He was arrested because his views went against the beliefs of the Church.

15. E. Galileo ( )

16. Assessment: Group Modeling
Each person in group will be a different object (with a sign)
Outside, teacher will call out an astronomer and group needs to show each objects movement
Don’t forget, the same side of the Moon always faces Earth.