Lesson 3+4

123456789101112
Across
  1. 3. all of space and everything in it
  2. 7. brightness its brightness seen from Earth
  3. 10. group of single stars
  4. 11. decide
  5. 12. blue-white core left behind and cools
Down
  1. 1. universe exploded
  2. 2. explosion
  3. 4. distance that light travels in one year
  4. 5. a large cloud of gas and dust containging an immense volume of material.
  5. 6. brightness brightness it would have if it were at a standard distance from Earth
  6. 8. first stage of a star's formation
  7. 9. examine