Rocket Men: The Daring Odyssey of Apollo 8 and the Astronauts Who Made Man's First Journey to the Moon

by Robert Kurson

In many ways, the story of the Moon is a story of its two sides. The near side, which has been facing Earth for billions of years, is marked by dramatic contrast between light and dark sections, which can easily be seen from Earth with the naked eye. The light areas are the highlands, covered with craters and rolling with hills and mountains that can rise miles above the surface. The dark areas are called mare (mare is Latin for “sea”; the plural is maria). The maria cover about one-third of the near side and are much smoother than the highlands, with far fewer craters, an unusual coda to a violent story. For billions of years, the Moon was bombarded by asteroids, comets, and other debris. The lunar surface is a record of those impacts, each of its round craters, with its sharp rim and rising edges, a snapshot of a collision. Some of the most massive impacts excavated huge basins with fractured floors that allowed molten magma to ooze up from the Moon’s mantle and fill them in, solidifying into a dark, smooth basalt that became the maria. These giant impacts were the climax of an era of bombardment that marked the Moon’s initial evolution. The formation of the maria occurred long after the basins were formed, in some cases perhaps by a half billion years or more, so they are younger than the light-colored highlands. The maria are also relatively free of craters, suggesting that the lunar landscape appears much the same today as it did three billion years ago. The far side ...