Earth, Moon, and Sun Vocab

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Across
  1. 1. a planet outside our solar system
  2. 4. the relative size of things
  3. 6. a moon outside our solar system
  4. 7. or easier to see
  5. 8. something we observe to be similar over and over again
  6. 9. the amount of time it takes for a planet to complete one orbit around a star or stars
Down
  1. 2. when the Moon is completely dark
  2. 3. the border between light and dark on the Moon
  3. 5. an object, diagram, or computer program that helps us understand something by making it
  4. 7. the star that is the main source of light at the center of our solar system