Questions+from+Class

Earth & Space Science is such a broad subject. So..... as unanswered questions are raised during class, I will post them here. The first student who correctly answers the question by emailing me (mchughc@nasdschools.org) a response/explanation will be eligible for extra credit. Don't forget to include your name with your response, and to include a link to your sources. Please provide complete correct responses.
 * ==Unanswered Questions from Class==

1. Which rocks or minerals can be smashed together to create sparks?

2. Why does star formation (stellar life cycle) take so long?

3. Why do planets usually form one ring in one direction and not many in different directions?

4. Is the debris more dense in the asteroid belt (between the orbits of mars and jupiter, or in the Kuiper belt (far beyond the orbit of pluto)? || ==== ||