Across
- 3. This galaxy is known as_________
- 4. Stars twinkle because of elements being converted over to other elements, which gives off _____
- 5. how long ago were there at least islands of continental crust on earth
- 9. Earths iron core creates a magnetic field which protects the planet from ________
- 10. what are scientists able to calculate from the radioactive elements found in a meteorite that decay at a particular rate
- 13. If we imagine earth Earth's total 4.5 billion year history to be over the span of one day how long ago did humans begin to walk the earth
- 14. special kind of water scientists look at in the ocean and comets to see if proportions match
- 15. was the moon closer or farther when the earth was younger
- 17. what processes formed the first clouds
- 18. ______is the dominant scientific theory that occured 15 billion years ago that formed the universe
- 19. _____of the clouds made heavy rain fall
- 20. in 6 billion years, the sun will hypothetically turn into a ________
Down
- 1. what are the scientists trying to determine when they look at the age of zircons in australia
- 2. how many years did heavy rain fall before the oceans were formed
- 6. how quickly is the moon moving away from the earth per year
- 7. what name do scientists give to earth when the outer surface was completely molten
- 8. during this time when the earth was liquid rock, what type of elements sank towards the earth's center
- 11. what type of object can give information about the conditions in which the solid planets formed
- 12. the explosion of a star
- 16. what is the name of the small early planets, which formed through gravitational attraction attraction reaching sizes of a few miles to eventually the size of our moon