Across
- 2. huge group of single stars, star systems, etc. bound together by gravity
- 7. this model observed that the moon revolved around the earth
- 10. methane give this planet a blue green color
- 11. path around the sun
- 13. revolves around the Sun
- 14. debris left by colliding asteroids or dispersing comets
- 15. distance that light travels in one year
- 18. patterns of stars in the night sky
- 20. units measure distances among the objects int he solar system
Down
- 1. used to be a planet
- 2. this model thought planets, sun and moon revolved around the Earth
- 3. closest planet to the sun
- 4. extremely dense atmosphere
- 5. system born 4.6 billion years ago
- 6. planet with the great red spot
- 8. day when Earth's rotation axis is leaning along Earth's orbit, neither toward nor away from the sun
- 9. day when Earth's rotation axis is the most toward or away from the sun
- 12. the red planet
- 13. elongated closed curve
- 16. happens every 365.24 days
- 17. water exists on this planet
- 19. the nearest star to the Earth