Placeholder Puzzla

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Across
  1. 3. Space telescope named after astronomer Edwin Hubble
  2. 5. Queen of Pop
  3. 6. Longest river in the world
  4. 8. Singer known for "Single Ladies"
  5. 11. Italian city known for its canals
  6. 13. Last name of a famous reality TV family
  7. 14. King of Rock and Roll
  8. 15. Director of "Pulp Fiction"
  9. 16. Singer known for "Umbrella"
  10. 19. Largest rainforest in the world
  11. 20. Famous British rock band from the 60s
Down
  1. 1. Iconic tower in Paris
  2. 2. Large system of stars, such as the Milky Way
  3. 4. Renowned physicist who developed the theory of relativity
  4. 7. Famous painter who co-founded the Cubist movement
  5. 9. Highest mountain above sea level
  6. 10. Particle found in the nucleus of an atom
  7. 12. Largest hot desert in the world
  8. 17. U.S. state known for its tropical islands
  9. 18. Famous composer from the classical era