yadiel's puzzle

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Across
  1. 3. The linear relation between the distance to a galaxy
  2. 4. Long, spiral pattern of bright stars, star clusters, gas, and dust
  3. 7. spheroidal cloud of stars at the center of most spiral galaxies
  4. 8. Nonluminous material that is detected only by its gravitational influence.
  5. 9. All material confined to the plane of the galaxy.
  6. 12. An irregularly shaped cluster that contains fewer than 1000 galaxiesLocal Group
  7. 13. A cluster containing more than 1000 galaxies
  8. 14. Object of known brightness that astronomers use to find distance
  9. 15. The effect of the focusing of light from a distant galaxy
Down
  1. 1. A region of the galaxy’s disk in which gas heated by supernova explosions
  2. 2. part of the galaxy including all matter in a spherical distribution around the center
  3. 5. A unit of distance equal to 1 million pc.
  4. 6. spiral galaxy containing a thin scattering of stars
  5. 8. The combined calibration of distance indicators used by astronomers
  6. 10. A cloud of gas collapsing gravitationally to become a galaxy.
  7. 11. The cluster of about 40 nearby galaxies