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