Concept

Drake Equation

Also Known As Green Bank Equation Named after the National Radio Astronomy Observatory's Green Bank facility, where Frank Drake convened the 1961 meeting that produced the equation.

Astrobiology and the Search for Life

A formula combining astronomical, biological and sociological estimate factors, such as star formation rate, the fraction of stars with planets, and the lifetime of a communicating civilization, to produce an order of magnitude estimate of the number of communicating extraterrestrial civilizations in the Milky Way. Devised as an organizing framework for an early SETI conference rather than a rigorous predictive tool, it is widely regarded as illustrative rather than quantitatively reliable because most of its terms are essentially unconstrained by data.

Facts

Concept Domain

Astrobiology 1

Formulated Year

1961 1

Proposed By

Frank Drake 1

FAQs

What values do scientists use in the Drake Equation today?

They vary widely; some terms are now well measured (star and planet formation rates), others remain guesses (odds of life arising, civilization lifetime).

Frank Drake devised the equation in 1961 as a way to organize discussion at a Green Bank meeting, not to produce one authoritative number, and the values plugged into it still vary enormously by researcher. Several of its terms, such as the rate of star formation and the fraction of stars with planets, are now measured far more precisely than in 1961 thanks to exoplanet surveys; others, such as the fraction of habitable planets where life actually arises or the average lifetime of a communicating civilization, remain essentially unknown, so estimates of the final answer still range from less than one to many millions.

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