The Drake equation isn’t really an equation. It’s a series of questions that help us to work out how many intelligent civilizations in the galaxy there are with the ability to communicate.

## Origin

The Drake equation was formulated by Dr. Frank Drake of the SETI institute, and is still used by scientists today.

## How to do a Drake equation

This is a Drake equation:

N = N* x Fp x Ne x Fi x Fc x L

«N*» represents the number of new stars born each year in the Milky Way.

Answer: Our galaxy is about twelve billion years old and contains roughly three hundred billion stars. So, on average, stars are born at a rate of three hundred billion divided by twelve billion equaling to twenty-five stars per year.

«Fp» is the fraction of these stars that have planets orbiting them.

Answer: Current estimates range from 20% to 70%.

«Ne» is the number planets per star that are capable of sustaining life.

Answer: Current estimates range from 0.5 to 5.

«Fl» is the fraction of planets in «Ne» where life evolves.

Answer: Current estimates range from 100% (where live can evolve, it will) down to close to 0%.

«Fi» is the fraction of habitable planets where intelligent life evolves.

Answer: Estimates range from 100% (intelligence has such a survival advantage that it will certainly evolve) down to near 0%.

«Fc» is the fraction of planets with intelligent life capable of interstellar communication.

Answer: 10% to 20%.

«L» is the average number of years that a communicating civilization continues to communicate.

Answer: This is the toughest of the questions. I f we take Earth as an example, we’ve been communicating with radio waves for less than one hundred years. How long will our civilization continue to communicate with this method? Could we destroy ourselves in a few years or will we overcome our problems and survive for ten thousand years and more?

Result: When we multiply all of these variables together, we come up with:

«N», the number of the communicating civilizations in the galaxy