Earth Rotation Puzzle

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Across
  1. 3. Circular movement where something turns around a point
  2. 4. What goes up, must come down
  3. 6. system A system that has at least one Sun and planets
  4. 7. An invisible line that is in the middle of a planet's rotation
  5. 8. Billions of these exist in the solar system
Down
  1. 1. This happens when the Earth completes 1 full orbit
  2. 2. A group of stars that make an image
  3. 5. When a planet moves around the sun