Chapters 15 and 16 Crossword

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Across
  1. 3. We can estimate its luminosity without having to know its distance (2 words).
  2. 4. The study of the universe as a whole
  3. 5. A collection of stars held as a group by gravity
  4. 6. The value of Hubble's _________ indicates the expansion rate of the universe.
  5. 8. A star whose apparent brightness changes predictably with time.
  6. 10. Very luminous, central portion of galaxies(3 words)
Down
  1. 1. A famous cycle occurring inside spiral galaxies (3 words)
  2. 2. A method that uses the temperature of main sequence stars and their apparent brightness to determine their distance (2 words)
  3. 7. Molecular gas clouds compressing in the _________ __________ of galaxies form new stars.
  4. 9. Wide, flat, gas-rich component of spiral galaxies