Across
- 3. Orbits a planet in space
- 6. Mountain that erupts lava
- 8. Tracks days and months
- 9. Gas essential for breathing
- 11. Tool that shows direction
- 13. Huge system of stars
- 15. Long travel from one place to another
- 17. Place to borrow books
- 18. Natural home of an animal
- 20. Powers devices and lights
Down
- 1. Framework of bones in body
- 2. Brain's ability to recall
- 4. Activity to stay fit
- 5. Precious stone, hardest natural material
- 7. Reuse of waste materials
- 10. Force pulling us to Earth
- 12. Tiny organisms, some cause infection
- 14. Fairness in treatment
- 16. Ancient Egyptian structure
- 19. Measures temperature