Science and nature journalist Boyle opens in 1943 with the Marine invasion of the Japanese-held island of Tarawa. Planners expected high tide to allow landing craft to pass over the reefs. Stuck, the soldiers were forced to wade to shore under fire, and more than 1,000 were killed. The lesson: Ignore the Moon at your peril. Most readers know that the Moon influences the tides, but this is just the tip of the iceberg. Rewinding the clock, the author delves deeply into prehistoric artifacts, monuments, cave art, and cryptic etchings on bones and stones, and she agrees with archaeologists that these markers mostly functioned as time reckoners for ceremonies and seasonal planning. Then, “as the first literate civilizations arose in Mesopotamia and Egypt, the Moon became…a recorder of events; a predictor of fates; an instrument of might; and a god in its own right.” In the final 100 pages, Boyle turns from calendars and myth to astronomy. Greek thinkers delivered an occasional insight, but it was Enlightenment figures who determined that the Moon was a physical body no less than the Earth. Because of its huge relative size (compared to other planet satellites), astronomers consider the Earth-Moon a dual planetary system. The Moon’s gravity stabilizes Earth’s rotation and wobble, which means that it stabilizes the climate. Boyle emphasizes that life may have been impossible without the Moon, and it plays an essential role in the growth, mating, feeding, and reproduction of countless plants and animals. The author does not treat the Apollo moon landing as an expensive technological spectacular but a scientific triumph. Rocks brought back turned out to be identical with those on Earth, suggesting that the Moon was torn from the Earth, likely from a planetary collision, and has evolved in predictable ways.