In this book, Jeffrey Jerome Cohen and Lindy Elkins-Tanton explore what happens when we think of the Earth as an object viewable from space. As a “blue marble,” “a blue pale dot,” a spaceship, an organism, or (as Chaucer described it) “this litel spot of erthe,” the solitary orb is a challenge to scale and to human self-importance. Beautiful and self-contained, the Earth suspended in cold blackness turns out to be far less knowable than it at first appears: its vast interior is after all an inferno of incandescent and yet solid rock and a reservoir of water vaster than the ocean, a world within the world. Viewing the Earth from space also invites both comparisons to its sister planets, and the subsequent dive into the abyss of scale: how can humans apprehend the distances, the temperatures, and the time scale on which planets are born, evolve, and die?