Astro 120  Fall 2005
Essay Question for Exam 3

You will be asked to answer this question during Exam 3 on Monday, December 12. Please think about how you will answer this question before the exam, and write your answer during the exam time.

PART II: ESSAY (20 points): Answer the question on this sheet front and (if needed) back only.

Name: _________________________        Section Number:________

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.

(12 points) The term fL 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 that provide appropriate conditions for life to develop. In a single brief essay, describe how EACH of the terms leading to fL restrict stars and planets to those that can support life.

In other words, what are the restrictions on host stars and on their planets that need to be made before we can consider if life could develop there? Which terms in the Drake Equation take these into account? How do those terms take the life question into account?

(8 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?