"After a few billion years of bearing witness to life on Earth, of watching one hundred billion humans go about their day-to-day lives, of feeling unbelievably lonely, and of hearing its own story told by others, the Milky Way would like a chance to speak for itself. All one hundred billion stars and fifty undecillion tons of gas of it. It all began some thirteen billion years ago, when clouds of gas scattered through the universe's primordial plasma...