Early Astronomers

3. The first to propose a heliocentric model.
5. Model with the sun at the center.
7. Formulated and tested the Law of Universal Gravitation.
8. Concluded that the Earth is shaped like a sphere.
11. Accurately provided measurements of stars and planets before the telescope.
12. Distance of the Earth to the sun is 93 million miles.
13. The apparent motion of a planet moving backwards.
14. Law states that the path of a planet is an ellipse.
15. The measure of oval a closed circle is.
16. This law states that the closer a planet is to the sun, the shorter the orbital period.

1. The first to propose that Earth is a planet.
2. States that every object in the universe attracts every other object.
4. Discovered retrograde movement.
6. Discovered the three laws of planetary motion.
9. Model with the Earth at the center.
10. This law states that equal areas are covered in equal time as a planet revolves around the sun.