science lesson 4 / 3

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Across
  1. 2. brightness seen from earth
  2. 6. large cloud of gas and dust
  3. 7. a bright explosion
  4. 11. brightness the star would have
  5. 12. large telescopes
Down
  1. 1. blue-white core is left behind cools
  2. 3. all of space and everything in it
  3. 4. group of single stars
  4. 5. the universe then exploded
  5. 8. more accurate scale of the entire solar system
  6. 9. the distance light travels in one year
  7. 10. cloud of gas and dust with enough mass