Photo summarizing the Drake Equation and possible variables.
The Drake Equation is our best estimate for the number of communicating extraterrestrial civilizations that exist in outer space with whom we might be able to communicate. The equation was originally devised in 1961 by the astrophysicist Frank Drake and focuses on a series of assumptions about the frequency of habitable planets and the likelihood of life developing on those planets. The equation has been used before as a way to understand the thinking behind the likelihood of extraterrestrial life in the Milky Way and the Universe. Unfortunately, the numbers behind each variable in the Drake Equation is a subject of debate with a defensible estimate for each leading to very different estimates for the number of communicating alien civilizations. For example, estimates of the number of habitable planets per solar system range from 0.1-5 planets per star. Similarly, the fraction of life that is intelligent is difficult to estimate, as we have only one example of a planet where life has developed and only have one where intelligent life has developed as a frame of reference. Despite the disparities between estimates for each variable, there has been much more discourse covering the possibility of intelligent alien life and more advances in the field of astrobiology since the introduction of the Drake Equation. The equation has highlighted the importance of searching for habitable planets and understanding the conditions that are necessary for life to develop. It has also led to the development of projects such as the SETI (Search for Extraterrestrial Intelligence) Institute, which uses radio telescopes to search for signals from other civilizations. The ongoing search for extraterrestrial life will improve the accuracy of our Drake Equation estimates.