Across
- 2. a planet's orbit would become more elliptical if these are placed further apart
- 4. this is when Earth is closest to the Sun in its orbit
- 5. the Earth is farthest from the Sun during this season
- 10. this astronomer's great contribution was his creation of a heliocentric model of our solar system
- 11. Newton's law of gravity states that the force between two objects depends on the objects' distance of separation and this
- 12. this would be the same for two planets if their average distance from the Sun is the same
- 14. according to the universal law of gravitation, this would happen to the force of gravity if the mass of one of the two objects would double
- 16. this astronomer found that the force of attraction between any two objects decreases with the square of the distance between their centers
- 18. this astronomer discovered that the orbits of planets are ellipses
- 19. "equal areas in equal times" describes which one of Kepler's Laws?
Down
- 1. this astronomer's model of the universe did not lead to significantly better predictions of planetary positions than Ptolemy's model because he used perfect circles for the orbits of planets
- 3. this shape has an eccentricity of "0"
- 6. this property of a planet does not affect its orbit around the Sun
- 7. this term describes the relationship between a planet's distance from the Sun and its period
- 8. a model that explains what we see in the sky while having the Earth orbit the Sun
- 9. this term describes the measure of the amount by which an elliptical orbit deviates from a circle
- 12. this astronomer's model was geocentric and included epicycles to explain retrograde motion
- 13. Galileo's observations of this planet offered direct proof of a planet orbiting the Sun
- 15. this is the point in an elliptical orbit where a planet is traveling the slowest
- 17. this is the season where Earth is moving the fastest in its orbit