Across
- 5. a linear or square rod
- 6. the envelope of gasses surrounding the Earth
- 8. Unwelcome intrusion
- 12. transform a planet to resemble Earth
- 13. the curved object of a celestial object
- 14. A person who observes the stars
- 15. Gaining control of a place
- 17. Required immediately
Down
- 1. any ground that remains completely frozen
- 2. A length of water wider than a strait
- 3. a celestial body that moves in orbit
- 4. the end of an event
- 7. A small body of matter from Outer Space
- 9. a person who is trained to travel in a spacecraft
- 10. The natural satellite of the Earth
- 11. to stop the process
- 16. A round solid figure