Across
- 3. an entire species dying out
- 4. repeating path that one object in space takes around another object
- 6. professionals who invent, design, analyze, build and test machines
- 8. main chemical in natural gas
- 11. an organism of microscopic size
- 12. the distance that light travels in a vacuum in one year
- 13. second planet from the sun and almost the same size as Earth
Down
- 1. Astrophage predator from Tau Ceti
- 2. a single celled microorganism that consumes energy from the Sun
- 5. Genetics passed from parent to child
- 7. layers of gas surrounding a planet
- 9. Advanced spider-like alien
- 10. memory loss