Our Moon: How Earth’s Celestial Companion Transformed the Planet, Guided Evolution, and Made Us Who We Are

Our Moon: How Earth’s Celestial Companion Transformed the Planet, Guided Evolution, and Made Us Who We Are by Rebecca Boyle

Our Moon (2024), by Rebecca Boyle, is an engrossing tour of our relationship with our closest celestial neighbor, full of the usual (and less familiar) facts, while delving into science, history, and culture as Boyle, as she says, explains “How the moon was made, how the Moon made us, and how we made the Moon in our image.”

Boyle starts off not on the Moon but on Earth three-quarters of a century ago with a 39-year-old marine waiting to begin the Allies’ attack on Tarawa Atoll, part of the Pacific campaign against Japan. Unfortunately, the tide the Allies had counted on for their landing didn’t come in, leaving the marines to “wade across six hundred yards of water … facing relentless fire from Japanese forces.” The reason things went so disastrously, so fatally wrong was the influence of the Moon. This scene is a starkly effective way of showing readers how that influence is not abstract but has real life and death consequences.

What follows is an engaging and informative trip through time and space. On the planetary physics side, besides the tidal impact, we get theories as to how the Moon formed (most centered on a collision with another planet named “Theia”), explanations of how the Moon affects Earth’s tilt (“Without the Moon, gravitational influence from Jupiter would push Earth around like a playground bully. Earth’s axis would tilt somewhere between zero degrees … and a vertiginous eighty-five degrees … such a wild wobble would make it hard for any life to survive for very long”), and how the Moon is “spiraling aways from Earth at a rate of about … 1.5 inches a year.”

On Earth we learn of the Moon’s influence on evolution, continent formation, body clocks, reproduction. And we travel through our changing mythic and intellectual relationship with the moon. In the earliest days, Boyle tells us, “The Moon stated out as a fertility symbols, a time counter, and a form of notation. It soon progressed to a new role as a time reckoner, enabling people to orient themselves in time, imagining the future as well as recalling the past … the Moon enabled the beginning of history.” From there humans began precisely tracking the Moon and trying to tease out its secrets and what it told us about our place in the larger universe. We follow those attempts from Babylon through to Mesopotamia, China, Persia, Greece, and then on into the Scientific Revolution with Galileo and others.

Some of this will be familiar to anyone who reads popular science or science history; Galileo, Kepler, et.al. are well-trod territory thoroughly embedded in the mind. But Boyle brings a lot new to the table as well. Or at least, a good amount unfamiliar or forgotten to me (and I read a lot of science history). Such as Thomas Harriot, the first person to draw the Moon through a telescope, beating Galileo by four months. Or the Greek Anaxagoras, who argued planets/moon were rock (evidenced by meteorites), catalogued eclipses and comets, and recognized the moon’s glow was reflected sunlight, all of which led him to be put on trial for heresy and forced to flee into exile. And while I’m familiar with ancient monuments that trace movements of the moon and sun and mark solstices, and have even visited some, I hadn’t heard of the Nebra sky disc or Berlin gold hat, let alone the fascinating story of the museum curator who went undercover to get hold of the former.

Similarly, we’re all well aware of the Apollo missions, but even here Boyle finds the tiny details, such as how “humans need to feel about 15 percent of Earth’s gravitational force to sense which way is up … [which] might explain why it’s so hard to walk on the Moon.” Or how “The moon has an acrid aroma, like fireworks that have just gone off,” according to those few who have actually smelled the Moon. In this section Boyle focuses much more on the science the missions enabled rather than the gee-whiz technological marvel of the achievement. One of my favorite parts is her visit to the site where NASA stores all the rocks brought back from the Moon, not just for the explanation of what we learned from them but for her infectious enthusiasm, as she describes her trip thusly: “The Lunar Sample Lab is no Holy Sepulchre of course, and the Moon rocks are not religious relics. But visiting them is a sort of devotional pilgrimage.” I can totally get behind that comparison.

Boyle closes with a look into the future, and human hopes for returning to the Moon. She is more than a little concerned about what that may entail. And in fact she argues instead that, “we don’t need to build a human settlement on the Moon. We don’t need to do anything at all to the Moon. The Moon cannot speak for itself. We have to speak for it … The Moon belongs to everyone, which means it belongs to no one.”

My only criticisms of Our Moon are relatively minor. One is that the narrative can be so digressive that it can at times feel a little disconnected, though if one waits long enough Boyle always cycles back to being on point. The other is that at times when Boyle brings up areas of scientific or historic debate, while she touches on the fact there is such a debate, I would have liked to have had a better, more detailed sense of the argument. So instead of lines like, “if Gaffney’s interpretation is correct” or “if this is true”, I wanted to know more about the alternatives. That said, Boyle does at times go further, either in the text proper or in the notes. As I said, the complaints are minor and certainly didn’t detract from the reading experience. By the end, you’ll know much more not just about the Moon as a physical presence but as a cultural and historical one as well.