No matter how conservative or optimistic we are, the statistics tell us that something like an astonishing one out of every seven stars must harbor a planet similar in size to the Earth, and at roughly the right orbital distance to allow for the possibility of a temperate surface environment. In other words, roughly 15 percent of all suns could, in principle, be hosting a place suitable for life as we know it.
Which is crazy, when you think about it. The likelihood of life not existing elsewhere becomes very small with these ratios.
But to discover whether or not we are alone, whether or not something akin to this Earth has happened somewhere else, and perhaps, just perhaps, whether or not there are other minds, on other worlds, thinking these same kinds of thoughts? That’s big, perhaps the biggest thing that could ever happen to a species.