Drake Equation

Devised by Dr. Frank Drake in the 1960s, the Drake equation supposedly allows a person to calculate the number of extraterrestrial civilizations in the galaxy that might be close enough to communicate with Earth. To use the Drake equation, a person must first estimate the rate of star formation in the galaxy, the number of stars with planets, the average number of planets around each star that might be able to support life, the fraction of those planets that might actually support life, the fraction of those life-supporting planets that might actually have intelligent life, the fraction of those planets with intelligent life that might have a civilization able to communicate with Earth, and the number of years such a civilization might have been in existence. All these fractions would then be multiplied by each other; the resulting product’s numerator would be divided by the denominator to arrive at the final answer, which varies depending on the original estimated numbers in the equation.

People who do not believe that extraterrestrial life exists at all end up with an answer of zero, but those who are certain there are many extraterrestrial civilizations have been able to make it come out to five thousand or more. But despite this element of subjectivity, positive results from the Drake equation were used in part as justification for the creation of the Search for Extraterrestrial Intelligence, or SETI, a project that searches for intelligent life by using radio telescopes to pick up radio waves from space.


  • the SETI Institute


The Greenhaven Encyclopedia of Paranormal Phenomena – written by Patricia D. Netzley © 2006 Gale, a part of Cengage Learning