Emma's crossword puzzle

123456789
Across
  1. 4. smaller than a constellation
  2. 6. dirty snowballs
  3. 7. first to believe in heliocentric
  4. 8. formed from debris
  5. 9. only planet with rings
Down
  1. 1. pluto
  2. 2. the queen
  3. 3. many have irregular shapes
  4. 5. closest to the sun
  5. 8. shooting stars