Inner vs Outer Planets

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Across
  1. 2. celestial
  2. 3. earth's sister planet
  3. 6. layers of gas surrounding a planet
  4. 8. Mercury, earth, venus, mars
  5. 9. similar to earth
Down
  1. 1. planet with no atmosphere
  2. 2. the red planet
  3. 4. a planet with rings
  4. 5. to circle around
  5. 7. planets that are further away from the sun