The Inner Planets

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Across
  1. 2. this planet has a red powdery dust covering its surface due to iron in the soil
  2. 3. this is the only object in the solar system other than Earth that humans have set foot upon
  3. 5. this is so thin on Mercury making it hot and cold and susceptible to asteroid impacts
  4. 7. this planet has the slowest rotation of any planet in the solar system
  5. 8. Earth is the only planet whose surface is divided into these
  6. 9. clockwise spin of a planet about its axis
  7. 11. counterclockwise spin of a planet
  8. 13. this planet has liquid water and an energy source
  9. 14. this is the unit used to measure the average distance between the sun and the Earth
Down
  1. 1. Mars is the only planet to have strong winds causing these which can cover the planet
  2. 4. four, small, dense, rocky planets
  3. 6. effect carbon dioxide is trapped on Venus and builds up causing this
  4. 10. water Earth is the only planet that has this
  5. 12. this planet has the most extreme temperature range in the solar system
  6. 15. accounts for most of Mercury's interior