Professor Frank Drake offered an equation that assist
in evaluating the number of noticeable extraterrestrial civilizations in the
Milky Way galaxy. The equation is still considered as a vital part of his. Essentially,
Drake decided to outline a series of regulating factors, so that we could add
the total number of recognizable stars, then scope way down to get to some approximation
for how many might have civilizations that we could actually be able to contact.
The resulting Drake Equation is one of the most stimulating result of math I've
ever seen. The Drake equation states that:

If that's still too math-heavy for you, just simply
watch this awesome explanation by Carl Sagan in this eight-minute video: