The Universe

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Across
  1. 5. matter that we cannot see but know it exists
  2. 8. violent explosion that occurs in a star's core succumbs to gravity
  3. 12. group of hundreds of thousands of stars
  4. 13. appear as a rotating disk of gas and dust
  5. 14. the study of the universe
  6. 15. galaxy that contains few million to a billion stars
Down
  1. 1. gravitational collapse that shrinks the star's core to a glowing white sphere
  2. 2. two stars orbiting each other
  3. 3. nuclei from two different atoms combine to form one new atom
  4. 4. measurement used for stars relatively close to Earth
  5. 6. our galaxy
  6. 7. shift of the absorption bands towards the red end of the spectrum
  7. 9. group of stars
  8. 10. galaxy that is not elliptical or spiral
  9. 11. biggest group of stars; contains hundreds of thousands of stars