1. What is an active galaxy? List the different kinds of active galaxies. How do they differ from one another? 2. Why do astronomers believe that the energyproducing region of a quasar is very small?...

1. What is an active galaxy? List the different kinds of active galaxies. How do they differ from one another?

2. Why do astronomers believe that the energyproducing region of a quasar is very small?

3. What evidence indicates that quasars are extremely distant active galaxies?