If we are optimistic in our assumptions about the development of ...

[Wadzanai]

If we are optimistic in our assumptions about the development of life and intelligence, then the number of technological civilizations currently in the galaxy should equal the
 
  A) average lifetime of a civilization.
  B) number of stars in the galaxy's habitable zone.
  C) average number of planets per star.
  D) number of stars forming per year.
  E) average number of planets that produce life.

Question 2

Why are star clusters ideal sites to study stellar evolution?
 
  What will be an ideal response?

[nital]

Answer to Question 1

A

Answer to Question 2

All members are about the same age, composition, and distance, so the brighter ones are really more luminous. They still differ in mass, so the more massive ones evolve a lot faster.

[Wadzanai]

Excellent

[ghepp]

Great answer, keep it coming