Drake Equation: How Many Of Them Are Out There? Some astronomy authors are so bold as to publish their guesses for all of the terms in the Drake equation even though estimates of n E and f l are only rough and values quoted for the last three, f i , f c , L, are just wild guesses. I will not publish my values for the last few terms because I do not want to bias your efforts in trying come up with a value for N. We do know enough astronomy to make some good estimates for the first two terms. The current star formation rate is about 2 to 3 stars/year, but in the past it was much larger so I quote the average value of 20 stars/year. The fraction of stars that are single, of medium temperature, and that would have any chance of life-filled planets orbiting them is about 1/50 = 2%. Proto-planetary disks have been detected around some stars and astronomers are now just beginning to detect planets around solar-type stars. See the end of the Solar System Fluff chapter for a discussion of finding extrasolar planets and web
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