Across
- 2. earths only satellite
- 5. the lightest gas
- 7. orbit
- 9. 78% of earth's atmosphere
- 10. huge collection of stars and planets
Down
- 1. star at the center of our solar system
- 3. 20% earths air
- 4. any planet outside of our solar system
- 6. force that keeps us on the ground
- 8. plasma held together by gravity