Across
- 1. used to be a planet
- 4. first element on the periodic table
- 6. variable that scientist changes
- 8. step before a black hole
- 10. star in our solar system
- 12. result of nuclear fusion
- 15. gravity cannot escape
- 16. red planet
- 17. planet with the most rings
- 18. the sun is a kind of
- 19. first planet
- 20. educated guess
Down
- 2. planet on its side
- 3. variable the scientist measures
- 5. not big enough to be a planet
- 7. named after god of the sea
- 9. named after goddess of love
- 11. turning hydrogen into helium
- 13. our planet
- 14. biggest planet