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There is on average one planet orbiting every star in the Universe \citep{2013ApJ...764..105S, 2012Natur.481..167C}. If this comes as an exciting news, you might wanna have a look at \href{https://www.authorea.com/10997/}{previous post} in this series. Just in our Our  Galaxy this means we have (the Milky Way) is an immense disk of gas and stars with a diameter of about 100 000 light years, hosting about  100 billions planets. Since we have stars and therefore also  about 100 billions planets. Take a deep breath.  Now, it turns out the Milky Way it's just one of the 100  billion galaxies in the that populate our  Universe, a colossal expanding stretch of spacetime with an age of 13.7 billions years.  The math is therefore simple:  there are about 10,000,000,000,000,000,000,000 = $10^{22}$ planets out there. But how many of these planets host life? And in particular,\textbf{ how many planets host intelligent life we might be able to communicate with}? In order to estimate the number of technological civilizations that might exist among the stars, in 1961 Frank Drake proposed the following simple equation