What equation is used to estimate the number of active extraterrestrial civilizations in the Milky Way?

The equation, formulated by Frank Drake, is not a real estimate of aliens in the galaxy, but is a tool that can help guess their probability. It includes such variables as the fraction of planets that can support life, the fraction of life that can become intelligent, and the fraction of intelligent civilizations that can develop detectable signals into space.

Asked by Ben Jenkins · Last updated 2 years ago · 2.8K views