Constellations & the night sky

1. What is a constellation?
2. How many constellations are there?
3. Is the "Big Dipper" a constellation?
4. When were the constellations named?
5. What are the zodiac constellations?
6. What is the largest constellation?
7. What is the smallest constellation?
8. Why can't some stars be seen?
9. Why do stars rise about four minutes earlier each night?
10. Why do we see different stars in different seasons?