Across
- 2. Largest object in the solar system
- 4. Earth does this once a year, around the Sun
- 9. Small and rocky
- 10. Carl Sagan said that we are made of this
- 11. Small and icy
- 12. Energy generation mechanism in stars
- 16. Beginning of the universe
- 17. Collection of Sun, planets, orbiting material
- 20. The universe is doing this all the time
Down
- 1. Collection of galaxies held together by gravity
- 3. Earth centered
- 5. Earth's average orbital distance
- 6. Sun centered
- 7. Earth does this each day on its axis
- 8. Pluto is now one of these
- 13. Our galaxy is this type
- 14. All matter and energy
- 15. Our group of 40 nearby galaxies
- 18. Distance light travels in one year
- 19. Our galaxy