Space

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Across
  1. 3. Planet with fastest rotation (7)
  2. 8. Colour of Mar's sunset (4)
  3. 9. Famous astronomer (7)
  4. 10. Vesta is which type of celestial body (8)
  5. 11. Brightest planet in the night sky (5)
  6. 14. Name of the Sun's outermost atmosphere (6)
  7. 15. A highly magnetised rotating neutron star (6)
  8. 17. There are 181 of these in our solar system (5)
  9. 18. Protects Earth from radiation (10)
  10. 19. Smallest planet in our solar system (7)
  11. 20. How many stars make up the Big Dipper (5)
  12. 21. Only planet not named after Greek gods (5)
Down
  1. 1. Phenomena that keeps planets in orbit around Sun (7)
  2. 2. The moon Titan orbits this planet (6)
  3. 4. The path travelled by a celestial body in space (5)
  4. 5. Planet with the most moons (6)
  5. 6. 27 percent of the universe is composed of this (4,6)
  6. 7. First man to walk on moon (4,9)
  7. 10. Study of the stars, planets and galaxies (9)
  8. 12. Constellation that represents a hunter and weapons (5)
  9. 13. Large group of stars, dust and gas (6)
  10. 14. Famous asteroid (5)
  11. 16. Planet with supersonic winds (7)