CROSSWORD PUZZLE

1234567891011121314151617181920
Across
  1. 2. a space that does not contain anything(not even air)
  2. 4. the branch of science that studies celestial bodies
  3. 7. the study of earthquakes
  4. 9. layer of gases surrounding a planet or other celestial body
  5. 10. group of stars that resembles a familiar figure
  6. 12. a person who studies birds
  7. 16. The amount of space occupied by any object
  8. 17. movement of earth around sun
  9. 18. that gives off light
  10. 19. amount of water vapor in the air
  11. 20. collection of cells
Down
  1. 1. a natural object that moves round a bigger object in space
  2. 3. medical device for listening to internal sounds of human body
  3. 5. conversion of water vapour into liquid water
  4. 6. awake and active at night
  5. 8. Material that passes electricity through it
  6. 11. Ability of a substance to get dissolve
  7. 13. body's ability to resist infections or illnesses
  8. 14. a device that enables you to measure temperature
  9. 15. nutrient that provides instant energy to the body