Across
- 4. hottest planet of solar system
- 5. hot molten rocks inside Earth
- 7. this gas comprises 78% of air
- 11. a part of the thermosphere
- 12. layer in which jet planes fly
Down
- 1. natural satellite of Earth
- 2. meteoroids burn up in this layer
- 3. a natural calamity
- 6. person trained to travel in spacecraft
- 8. study of earthquakes
- 9. three-quarters of moon
- 10. an important greenhouse gas