Across
- 4. sword
- 5. 5th planet from the sun
- 6. Commander of a fleet or navy squadron
- 7. aircraft for stopping hostile aircraft
- 11. 3rd planet from the sun
- 12. intense beam of monochromatic light
- 13. opponent
- 15. 1st letter of the greek alphabet
- 17. part of an advancing army or naval force.
- 18. natural satellite for a planet
- 19. quantity of energy
- 20. deputy acting for superior
Down
- 1. high ranking army officer
- 2. vehicle for space travel
- 3. interferes or alters something else
- 8. radioactive metal
- 9. a type of battleship
- 10. support
- 14. first version of something
- 16. ionized gas made of positive ions & electrons