? Across 3. Pluto 5. Galileo 6. Solar system 11. Galaxy 17. Telescope 19. Astronomical unit 21. Supernova 22. Star 23. Aurora borealis 24. Asteroids 25. Orbit 26. Curiosity ? Down 1. Planet 2. Terrestrial 4. Light year 7. Milky Way 8. Gas giants 9. Copernicus 10. Moon 12. Saturn 13. Comet 14. Nebula 15. Dwarf 16. Meteor 18. Sun 20. Constellation
