Across
- 4. 20th century cosmologist
- 5. once a planet, now a dwarf planet
- 8. first person to walk on the Moon
- 11. science of mapping stars and planets
- 14. first person to journey into outer space
- 16. astronomical body that orbiting a planet
- 17. Hg, a planet
- 18. small rocky body orbiting our sun
Down
- 1. a moon of Jupiter
- 2. "evening star"
- 3. "falling" or "shooting" star
- 4. gas that fuels our sun
- 6. a neutron star
- 7. study of celestial objects
- 8. nearest major galaxy to the Milky Way
- 9. seventeenth century astronomer
- 10. 'God of the sea' and a planet
- 12. space telescope
- 13. famous comet
- 15. type of Galaxy