Across
- 3. - A shooting star (6)
- 8. - The hottest planet in the solar system (5)
- 9. - A planet made mostly of hydrogen and helium (3,5)
- 11. - The coldest planet in the solar system (6)
- 12. - An imaginary line that determines day and night on Earth (4)
- 15. - An elliptical path undertaken by large objects in space (5)
- 16. - A term used to describe Pluto and Ceres (5,6)
- 18. - A group of stars that tells a story (13)
Down
- 1. - A chunk of rock ripped apart from the Earth that controls the tide (4)
- 2. - Clouds of dust and gas that are also know as "star nurseries" (7)
- 4. - A term used to describe a type of satellite born from an exploding star (7)
- 5. - A planet named after a God of War (4)
- 6. - The first element fused in the core of a star (8)
- 7. - The largest planet in the solar system (7)
- 9. - The force that gives rise to nuclear fusion within the core of a star (7)
- 10. - The closest galaxy to the Milky Way (9)
- 13. - A period of time determined by the Earth's axis (6)
- 14. - A remains of a meteor (9)
- 17. - The only known galaxy with life (5,3)