Big History Crossword Puzzle

8. This condition may result in a continuation of life on Earth.
9. A star will eventually consume all of these substances to power its nuclear fusion.
11. they formed out of a galaxy cluster.
12. They begin to light up all over the universe.
13. It is a energy.
16. they formed out of galaxies.
17. They produce enough helium to begin burning helium when the hydrogen fuel runs out.
18. It is the death and massive explosion of a star.
19. group of stars formed what?
20. These events are the Earth's way of maintaining equilibrium during periods of change.

1. The process by which the planet's chemical composition is determined.
2. created gas clouds by bringing together individual hydrogen and helium atoms.
3. What will only very large stars end up froming?
4. They are created from the atom clouds that are left over.
5. Some energy is converted when you add energy to a pot of water or a group of atoms.
6. It takes a lot of heat to fuse them together.
7. This was a relatively cool and uniform place before stars.
10. They will simply burn out if there isn't enough fuel.
14. They could be big and composed of gases or smaller and composed of rocks like our Earth.
15. Formed by the dramatic explosions of dying stars.