You will be asked to answer this question during Exam 3 on Tuesday, December 16. Please think about how you will answer this question before the exam, and write your answer during the exam time.

We discussed the Drake Equation at the end of this course. Please answer the following questions about the Drake Equation in terms of what you learned in Astro 120 this semester.
 

1. (15 points)
   The term f_L is the fraction of planets that have suitable conditions for life to develop that do, indeed, develop life on their surfaces. Before discussing this term, though, earlier terms in the Drake Equation considered other factors are that provide approrpriate conditions for life to develop. In a single brief essay, describe how the terms leading to f_L restrict stars and planets to those that can support life. In your essay be sure to address the following questions:
   1. What are the considerations that go into deciding if a planet can develop life? In other words, what are the restrictions on stars and on planets that need to be made before we can consider if life could develop there?
   2. Which terms in the Drake Equation take these into account?
   3. How do those terms take the life question into account?

2. (5 pts)
   Make your own estimates for each of the terms of the Drake Equation (feel free to use those determined in class if you agree with them, or use different values if you prefer) and briefly discuss (in a complete sentence or two) your reasons for adopting each value.

   What is your final value of N?