Puzzle 66

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Across
  1. 4. The theory Albert Einstein is known for.
  2. 7. The name for a speed greater than that of sound.
  3. 8. A planet which exists outside Earth's solar system.
  4. 10. The theory Charles Darwin is known for.
  5. 11. Sound too high to hear by humans.
  6. 15. The largest moon of Saturn.
  7. 16. The highness or lowness of sound.
  8. 17. The fear of dogs.
  9. 19. The man who launched eBay in 1995.
  10. 20. The largest moon in the solar system.
Down
  1. 1. He invented the first battery.
  2. 2. Units used to measure relative loudness.
  3. 3. A material that heat or electricity can move through.
  4. 5. He received the Nobel prize for developing the first nuclear-particle accelerator.
  5. 6. He discovered the laws of electrolysis.
  6. 9. He named the pacific ocean.
  7. 12. The century in which the battery was invented.
  8. 13. The planet named for an ancient messenger.
  9. 14. What is thought to cause the spots on Uranus.
  10. 18. A unit of food energy.