The Solar System Crossword Puzzle

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Across
  1. 3. Vast collection of stars, like the Milky Way
  2. 4. Known as Earth's "sister" planet
  3. 6. Earth-centered solar system model
  4. 9. Sun-centered solar system model
  5. 10. - Gaseous planets further from the sun
  6. 11. Italian astronomer and physicist
  7. 13. Earth's natural satellite
  8. 14. The center of our solar system
  9. 16. Planet with a tilted axis
  10. 18. Small rocky object in space
Down
  1. 1. Our home planet
  2. 2. Largest planet in our solar system
  3. 5. Closest planet to the Sun
  4. 7. Former ninth planet in our solar system
  5. 8. Eighth planet from the Sun
  6. 12. Rocky planets closest to the sun
  7. 13. The Red Planet
  8. 15. Known for its beautiful rings
  9. 17. Imaginary line around which Earth rotates