Horizon's Universe

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Across
  1. 4. An object that orbits a star
  2. 7. A huge group of stars, dust and gas bound together by gravity
  3. 8. A method that astronomers use to measure distances in space
  4. 9. A large cloud of dust and gas in space
  5. 11. The distance light travels in one year
  6. 12. An object that orbits a planet
  7. 13. A way that scientist write very large or very smaller numbers
  8. 14. An instrument that astronomers use to observe objects in space
  9. 16. The sun, the planets, and the other objects that revolve around it
Down
  1. 1. Earth's largest natural satellite
  2. 2. the galaxy in which we live
  3. 3. A ball of hot gas, usually hydrogen and helium
  4. 5. All of space and everything in it
  5. 6. The average distance between the Earth and the Sun
  6. 10. An explosion that formed and expanded the universe
  7. 15. The fuzzy outer layer of a comet