Across
- 6. happening after sth else (adverb)
- 7. related to the study of stars and other objects in space using physical laws
- 9. between stars
- 10. deserted, empty, uninhabited
Down
- 1. existing since the beginning of the universe/world
- 2. very advanced, complex
- 3. (people) who prefer staying at home rather than going out
- 4. antonym to contaminate
- 5. creatures from outside the Earth
- 8. proposed idea to state sth not yet proven