Abstract
It is traditional to discuss about extraterrestrial intelligence in terms of the celebrated Drake equation, with its estimates of habitable planetary systems, origins of life, evolution of technology, and so on. Although several factors are highly speculative, a subset of them, describing the number of habitable planets can be now stated more precisely with the help of new results from investigations in extra-solar planetary systems. Probabilistic estimations of the first factors provide about 50 millions habitable planets in the present Milky Way. A second approach is based on an integrated Earth system analysis. Combining the formation rate of Earth-like planets with estimations of extra-solar habitable zones (HZ) gives the number of habitable planets in the Milky Way over cosmological time scales. There was a maximum number of habitable planets around the time of Earth’s origin. If at all, interstellar panspermia was most probable at that time.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
