Astronomy

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Across
  1. 3. the method of ________ is used in measuring the distance to nearby stars.
  2. 5. the distance to an imaginary star whose parallax is 1 second of arc
  3. 7. the analysis of spectra
  4. 11. spectrums of stars
  5. 13. the state of an atom when unstable
  6. 15. speed toward or away from us along the line of sight
Down
  1. 1. the amount of angular change in a star's position
  2. 2. motion through space with respect to the Sun
  3. 4. longer wavelengths
  4. 6. in O type stars, gas atoms are _______, or broken up
  5. 8. the positions and motions of stars.
  6. 9. shorter wavelengths
  7. 10. a pellet of light
  8. 12. the smallest particle of an element
  9. 14. the positive charge on an atom