Portals into the Cosmos: crossword puzzle

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Across
  1. 2. : the study of stars and planets.
  2. 5. : the name of our galaxy.
  3. 7. : a group of stars that make a picture in the sky.
  4. 8. : the only planet in our solar system that sustains life.
Down
  1. 1. : the title of this magazine.
  2. 3. : "natural satellites" that can orbit planets.
  3. 4. : an instrument used to see far away.
  4. 6. : a force that not even light can escape from.