Astronomy

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Across
  1. 6. have a negative charge in an atom
  2. 7. a huge collection of gas, dust, and billions of stars and their solar systems
  3. 9. have a positive charge in an atom
  4. 10. you can physically touch dark matter(true or false)
  5. 13. dark matter has a ________________ effect on visible matter
  6. 15. have no charge in an atom
  7. 16. The reasoning behind dark matters name
  8. 18. dark matter holds a lot of _______
  9. 19. makes up 27 percent of the universe
  10. 20. dark matter can't be destroyed unless they ______ together
  11. 21. the universe is held together by _______
Down
  1. 1. first to propose dark matter
  2. 2. Last stage of the life cycle of a star
  3. 3. dark matter doesn't interact with the _____________
  4. 4. a subatomic particle that carries a fractional electric charge
  5. 5. makes up 70 percent of the universe
  6. 8. during the life cycle of a star after red supergiant
  7. 11. the temperature is ark matter is very ______
  8. 12. we only understand 3 percent of the ______ in the universe
  9. 14. everything in the universe is made of _____
  10. 17. the universe is always __________