Stars

5. a small insect that produces flashes of light when it flies at night
6. a group of objects of one type that have been collected by one person or in one place
9. a gas, one of the chemical elements, that is lighter than air and will not burn. (symbol He)
10. dry dirt in the form of powder that covers surfaces inside a building, or very small dry pieces of earth, sand, or other substances
13. A chemical reaction is the change that happens when two or more substances are mixed with each other. Chemistry
14. the sudden failure of a system, organization, business, etc.
15. a large ball of burning gas in space that is usually seen from earth as a point of light in the sky at night:
16. the area above the earth in which clouds, the sun, and the stars can be seen
17. A nucleus is the central part of an atom. see also neutron, proton. Topics Physics and chemistry
18. the center or most important part of something

1. the period between birth and death, or the state of being alive
2. a form of matter that is neither solid nor liquid and can increase in size to fill any container
3. the number 1,000,000,000
4. the part of every 24-hour period when it is dark because there is no direct light from the sun:
7. a place where young children and babies are cared for while their parents are somewhere else
8. a very young star that is still gathering mass from its parent molecular cloud.
11. the number 1,000,000
12. a cloud of dust or gas in outer space
18. a white or gray mass of very small drops of water or ice that float in the sky