The Milky Way contains at least 100 billion planets, or enough to have one for each of its stars, and many of them are likely to be capable of supporting conditions favorable to life, according to a new estimate from scientists at the California Institute of Technology in Pasadena, California (Caltech).
Of course, "favorable to life" doesn't mean "likely to have life exactly as we know it." Not to get too metaphysical, but which is worse? Being all alone in the universe? Or strongly suspecting there are other populated worlds that will come and go without us ever knowing anything about those who lived there? Planets passing in the night.