Space

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Across
  1. 3. gravitationally bound system of stars
  2. 6. distance around a circle
  3. 8. gravitationally curved part of an object
Down
  1. 1. star at the centre of the solar system
  2. 2. straight line that passes through the centre of a circle
  3. 4. round 3D object
  4. 5. Earth's only natural satellite
  5. 7. planet that human live on