jacob's crossword puzzle

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Across
  1. 3. the solid inner core of a comet
  2. 9. an imaginary pattern of stars in the sky
  3. 10. the fuzzy outlayer of a comet
  4. 12. a spherical region that surrounds the solar system
  5. 13. the brightness of a star as seen fom earth
Down
  1. 1. an oval shape, which may be elongated or nearly circular, the shape of the planet's orbits
  2. 2. a unit of measurement equal to earth's average distance from the sun
  3. 4. a model of the solar system in which earth and the other planets revolve around the sun
  4. 5. a doughnut shaped region that stretches from beyond neptune's orbit to about 100 timeseath's distance from the sun
  5. 6. a model of the unverse in which earth is at the center of the revolving planets and stars
  6. 7. an instrument that seperates light into colors and makes an image of the resulting spectrum
  7. 8. a natural satellite that revolves around a planet
  8. 11. a loose collection of ice, dust, and small rocky particles , tippically with a long narrow orbit
  9. 14. the brightness a star would have if it were at standard distance from earth