# Exoplanets and the Drake Equation

*Richard Lukens*

A highly modified Drake Equation was formulated to estimate the number of advanced technical civilizations (ATCs) per billion cubic light years in our galactic neighborhood as the product of a number of factors. Since evolution is a stochastic process (even including prebiotic chemistry), it could be estimated that an ATC would evolve on an extra-solar earthlike planet (exoEarth) within 500 million years of the time it took on Earth (4.5 billion years from formation of the planet). The factors entering the equation were estimated using a variety of techniques and data from the Gliese catalog of nearby stars (about 2000stars) and from the Interactive Extra-Solar Planets Catalog. The number of ATCs obtained by the forgoing considerations works out to 1.7 per billion cubic light years. Using Poisson statistics, it’s estimated that the likelihood of one or more ATCs within 200, 460, or 750 light years is 5.5%, 50%, or 95%, respecively. Since we’ve only been broadcasting 100 years, it’s likely that any ATC we contact will be relatively far advanced in science and technology.

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