Ask how many Earth-like planets there are, and the honest answer is that serious researchers give estimates spanning more than twenty orders of magnitude. At one end, essentially one, us, if the Rare Earth hypothesis is right. At the other, something approaching a hundred quintillion, if the rates we measure in the Milky Way hold […]
Ask how many Earth-like planets there are, and the honest answer is that serious researchers give estimates spanning more than twenty orders of magnitude. At one end, essentially one, us, if the Rare Earth hypothesis is right. At the other, something... [4995 chars]