Every generation has looked towards the heavens and wondered at the beauty of the Moon. Fifty years ago, a few Americans became the first to do the reverse—and shared with Earth-bound audiences the view of their own planet hanging in the sky instead.

Recently, the connection has been discovered to be even closer: a fragment of the Earth's surface was found embedded in a rock brought back from the Moon. And astronauts are preparing to return to the surface of the Moon after a half-century hiatus—this time to the dark side.

Oliver Morton explores how the ways we have looked at the Moon have shaped our perceptions of the Earth: from the controversies of early astronomers such as van Eyck and Galileo, to the Cold War space race, to the potential use of the Moon as a stepping stone for...