science crossword

123456789101112131415
Across
  1. 7. two thirds of all galaxies are barred
  2. 8. obvious disk and nuclear bulge
  3. 9. are very luminous
  4. 10. velocity of recession and distance
  5. 11. find mass of a galaxy
  6. 15. the merger of galaxies
Down
  1. 1. are round or elliptical contain no visible gas
  2. 2. measure distance
  3. 3. objects to map spiral arms
  4. 4. contain a disk of spiral arms
  5. 5. flattened cloud of billions of stars
  6. 6. a chaotic mix of gas and dust with no central bulge
  7. 12. a unit use by astronomers
  8. 13. spherical cloud of stars and star clusters
  9. 14. no light or energy