science crossword

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Across
  1. 5. a region of spacetime where gravity is so strong that nothing
  2. 6. chemical element with the symbol H
  3. 8. a plasma of hydrogen and helium
  4. 10. the Sun and the objects that orbit it
  5. 11. an atmospheric phenomenon
  6. 14. a vehicle or machine designed to fly in outer space
  7. 15. a small planetary-mass object
  8. 18. a person who is trained to travel in a spacecraft.
  9. 20. also known as a minor planet
Down
  1. 1. the distance that light travels
  2. 2. a gravitational bound system
  3. 3. Earth's only natural satellite
  4. 4. chemical element with a symbol he and atomic number of 2
  5. 7. the galaxy that includes our Solar System
  6. 9. an astronomical object
  7. 10. 4.5 billion-year-old star
  8. 12. a path planets take around the sun
  9. 13. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
  10. 16. stars that have burned up all of the hydrogen they once used as nuclear fuel
  11. 17. a dying star in the final stages of stellar evolution
  12. 19. controls and regulates the activities of the cell