This lively science history relates one of the great recent breakthroughs in planetary astronomy-a successful theory of the birth of the Moon. Science journalist Dana Mackenzie traces the evolution of this theory, one little known outside the scientific community: a Mars-sized object collided with Earth some four billion years ago, and the remains of this colossal explosion-the Big Splat-came together to form the Moon. Beginning with notions of the Moon in ancient cosmologies, Mackenzie relates the...