PS 6.2 Review

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Across
  1. 6. the second era of the universe (the current era)
  2. 7. a baby planet
  3. 10. a star ignites when it begins nuclear ______
  4. 12. at first, the universe was only a few _________ wide
  5. 13. the theory that explains how the universe formed
  6. 15. in the radiation era, no matter existed - only ______
  7. 16. the building blocks of life that formed from star explosions
  8. 17. a supported scientific explanation of an event or phenomenon
  9. 18. the epoch where stars first formed
Down
  1. 1. everything that exists
  2. 2. when matter clumps together
  3. 3. the first era of the universe was the _______ era
  4. 4. the first element that formed in the universe
  5. 5. scientists that study the universe
  6. 8. the four large outer planets
  7. 9. the four inner rocky planets
  8. 11. the theory that explains how the solar system formed
  9. 14. the universe started out as an extremely _____ object