Question

I know that this is the physics forum but no one's active on the earth science forum so can someone help me out? I'll give medal and fans!

Answer 1

1. What was the original reason for identifying and naming nebulas?

2. Are all double stars binary stars? Explain.

3. How can astronomers tell if groups of stars actually form a star cluster?

4.Until the twentieth century, how far did most people believe the observable universe extended?

5. What is a galaxy?What kind of galaxy is the milky way?

6. Are quasars related more to galaxies or to stars? Why?

7. True or false? Galaxies are held together by centrifugal force.