Across
- 2. the study of objects beyond Earth and how they interact
- 5. the distance light travels in one year
- 7. a science rule that has never been disproven
- 11. a.k.a. longitude
- 12. giant balls of hot plasma that give off radiation
- 13. the point in the sky directly overhead
- 14. the direction pointed in the sky measured in degrees
- 16. the distance from the Earth to the Sun
- 17. invented to try to explain retrograde motion
- 18. how high an object is above the horizon
Down
- 1. patterns seen in groups of stars in the sky
- 3. the movement of one object around another
- 4. oval shape of planetary orbit
- 6. the unit of distance most used by astronomers
- 8. Greek who calculated the radius of the Earth
- 9. an object that orbits a star but has not cleared the path of other objects
- 10. belief that the Earth is the center of everything
- 15. a collection of dust, gas, stars & planets