The number of planets on which complex life could exist in the Milky Way may be as high as 100 million. Researchers arrived at the number by computing a "Biological Complexity Index," which rates planets on a scale of 0 to 1.0, based upon characteristics assumed to be important for supporting multicellular life.
More from Gizmodo
I think Douglas Adams was right. They're out there, we are not just cool enough for them in our unfashionable end of one of the spiral arms of the galaxy.