Across
- 4. what the surface of the inner planets is made of
- 7. gases above the surface
- 9. a small, dark planet that has an extremely thin atmosphere
- 10. relating or similar to Earth (alternate name to inner planets)
Down
- 1. the red planet with a thin atmosphere
- 2. revolves around something; all planets do this in our solar system
- 3. the giant collection of planets that has a sun
- 5. a celestial body that orbits a planet - Mars has TWO of these
- 6. Earth's sister planet that is the hottest planet in the solar system
- 8. the only livable planet known by scientists right now