History of Astronomy

5. The force described by Newton that explained why planets and moons stayed in orbit
6. Tycho Brahe's assistant who was eventually able to make a heliocentric model based on ellipses and Brahe's data
9. Created a geocentric model of the universe that stood unchanged for thousands of years
10. Newton's Law that related force, mass, and acceleration.
11. A model of the universe (solar system) that has the sun at the center
15. Credited with being the father of astronomy - determined that the Earth was actually round
16. The planet that Galileo observed going through phases similar to the moon
17. A model of the universe (solar system) that has the Earth at the center
18. A Greek astronomer who was the first to suggest that the Earth might revolve around the sun and not the other way around

1. The planet that Galileo observed moons around adding powerful evidence for a Heliocentric model of the solar system
2. An astronomer working for Denmark who made detailed observations of planets over nearly 40 years
3. When a planet will appear to move backwards through the night sky for several nights
4. Smaller circles added into the larger orbits of planets to explain retrograde motion in a geocentric model
7. Major contributions to astronomy were refining our understanding of gravity and providing a mechanism
8. An Italian astronomer who made the first astronomical observations with a telescope. Responsible for major evidence of a heliocentric model.
12. A late renaissance astronomer who developed laws of motion that worked for both Earth and space.
13. Prussian astronomer during the renaissance who revived the idea of a heliocentric solar system
14. Kepler's Law that explained that planets move in elliptical orbits
19. Ancient Greek astronomer who also invented trigonometry