Across
- 2. years that it took for first surface to form
- 4. why stars shine
- 7. sun will become a red giant and engulf this
- 8. what planets formed through
- 9. turns hydrogen into helium
- 10. made discovery that universe is still expanding
- 14. is just right, keeps water accessible and in one spot
- 16. iron sinks to middle and lighter materials form surface
- 17. believed heat energy could form complex molecules of life
- 20. protects us from uv rays
- 23. releases volatile substances and water vapor
- 25. Huge rotating aggregations of stars, dust, and gas held together by gravity.
- 26. what stars form in
- 27. occured 2.5 billion years ago
- 28. chemical element that makes up planets, stars, oceans,and organisms
- 29. its clear so sun can penetrate
- 30. spinning skater that brings their arm in
Down
- 1. they are 3.4 -3.5 billion years old and are bacteria-like organisms
- 3. oldest rocks on earth
- 5. how stars were formed
- 6. had an experiment in 1953
- 11. included methane, ammonia, co2, and water vapor
- 12. star that blows up
- 13. provides for gentle tides
- 15. early steps of organisms forming organic building blocks
- 18. fell for 10 million years
- 19. formed in stanley millers experiment
- 21. what the sun is
- 22. Spiraled galaxy
- 24. earth is believed to have formed from these
- 31. sun will become this in 6 billion years