Across
- 4. planets that are like the Earth
- 5. gasses that surround a planet
- 9. the 4 planets closest to the sun
- 10. Earth's sister planet
Down
- 1. moves around repeatedly
- 2. known as the Red Planet
- 3. the 4 planets farthest from the sun
- 6. celestial object that orbits a planet
- 7. contains water and oxygen
- 8. has the shortest orbit around the sun