astronoy discussion#######

Discuss the causes, characteristics, and major features  of black holes.  Explain why the concept of a black hole does or doesn’t seem reasonable to you and provide some rationale for your views?     i need two paragraph for this discussion. and need two differen answer for this question.

   

1.

    

Describe a planetary nebula and its cause?

     

                             

           

2.    
What would the major impact on Earth be if the Earth remained in its present orbit and our Sun was 50% more massive than it is now?

                                    

   

3.   Under certain circumstances a white dwarf will go type Ia supernova becoming much brighter for a short period of time. What special circumstance is required for this event to occur? 

                                    

4.    
Why is a large mass required to have a type II supernova event?

                                     

5.    
If our Sun maintained its current mass, but suddenly collapsed and became a block hole, how would Earth’s orbit be affected?