CROSSWORD PUZZLE:Universe and Galaxy

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Across
  1. 5. cloud of gas and dust
  2. 8. fireball
  3. 9. longer wavelength
  4. 10. our solar system belongs
  5. 11. atomic, galactic, stellar
  6. 12. force that repels gravity
  7. 15. a group of stars forming patterns
  8. 17. explanation of a phenomenon
  9. 18. to swing or move regularly back and forth
  10. 19. earliest stage
Down
  1. 1. study of the origin and evolution of the universe
  2. 2. the cosmos
  3. 3. proposed the oscillating universe
  4. 4. BigBang and BigCrunch
  5. 6. no beginning nor end to the universe
  6. 7. named for the dominance of radiation
  7. 13. consists of billions of stars
  8. 14. shorter wavelength
  9. 15. remnants of bigbang
  10. 16. universe rapidly expanded