Planets!

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Across
  1. 2. Has polar caps made of carbon dioxide
  2. 4. Was originally going to be called "george"
  3. 6. Has wind so fast it breaks the sound barrier
Down
  1. 1. Causes Kirkwood gaps
  2. 2. the biggest crater is named the Coriolis crater
  3. 3. the planet with the least orbital eccentricity
  4. 5. Has the lowest density out of all the planets
  5. 7. IS TOTALLY A PLANET THE IAU DOESN'T KNOW WHAT ITS TALKING ABOUT
  6. 8. the planet with the most nitrogen-rich atmosphere