Unlikely Hero

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Across
  1. 2. extremely large
  2. 5. object so massive and dense that nothing can escape after falling in
  3. 7. force that attracts objects toward one another
  4. 8. a phenomenon that exerts a force on moving charged particles
Down
  1. 1. understandings
  2. 3. puzzling
  3. 4. hot flowing matter made up of charged particles
  4. 6. is the distance light travels in a year