Across
- 2. the planets' revolution around the sun
- 5. used to describe things relating to the sun
- 6. the name of science that studies space
- 7. the crust, mantle, outer core and inner core make up this layer of Earth
- 8. the layer of gases around the Earth
- 9. planets with a rocky surface or structure
Down
- 1. this layer covers 70% of the Earth's surface
- 3. a planet ______ on its axis
- 4. planets with no firm surface to stand on