Science lab

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Across
  1. 2. A cloud of gas and dust kept together by gravity
  2. 3. the "middle age" stars belong to this group
  3. 5. a galaxy that has "arms"
  4. 6. a cloud of gas dust that creates stars
  5. 8. the final stage of a massive star where it explodes
  6. 9. the invisible force that keeps things in place.
Down
  1. 1. a oval shaped galaxy
  2. 4. a galaxy that has no defineable shape
  3. 7. the result of a collapsed giant star that has a huge amount of mass
  4. 8. a sphere of gas that is extremely hot and bright