Across
- 4. Planet orbiting another star.
- 7. Solar system boundary.
- 9. Instrument for distant observation.
- 10. Largest gas giant.
- 12. Icy celestial body with a tail.
- 13. Boundary of the Sun's influence.
- 15. Small rocky body in space.
- 18. Farthest point from the Sun in an orbit.
- 19. Tilted, blue-green ice giant.
- 20. Central star of our system.
- 21. Vast system of stars.
Down
- 1. Magnetic field region.
- 2. Our home planet.
- 3. Distant, windy ice giant.
- 5. Celestial path around the Sun.
- 6. Earth's "sister" planet.
- 8. Closest point to the Sun in an orbit.
- 11. Polar light displays.
- 14. Ringed planet with distinct features.
- 16. Red planet with polar ice caps.
- 17. Closest planet to the Sun.