Since the beginning of time, the Moon has controlled life on Earth and shepherded the human mind through a spectacular journey of thought, wonder, power, knowledge, and myth. But this frenzied, multifarious, Earthly history disguises the truth of the Moon. As vivid and lively as our history with it has been, the Moon itself is quiet, barren, and still.
This was not always the case: When the Moon was young, it was livid with energy and heat, a magnetic field, oceans of lava, and maybe an active crust like the one that warps and wrinkles the face of our world. But no one was around for this lively phase. The only Moon we have ever known is the spectral one in our sky, the two-dimensional one, the cold and silent one.
Nothing happens there, except the occasional arrival of an asteroid or the briefly violent puff of a crashed or landed spacecraft. Nothing looks up, nothing breathes, nothing hopes.
When Apollo 11 astronaut Buzz Aldrin walked on the Moon in 1969, he described his surroundings as “magnificent desolation,” an interpretation that has yet to be bested. It’s difficult to liken the Moon to any where familiar, because anywhere familiar is a place on Earth.
Even from orbit, Earth looks and feels like home. Astronauts report that staring down on our planet is one of the most exhilarating things about being in space. We belong here. Earth’s razor-thin atmosphere, cloud tendrils, green-carpeted continents, and deep ocean blues beckon us.
Humans are sensory beings, and the Moon is a place devoid of any familiar sensory experience.
Not so for the Moon, according to Collins, who orbited it alone in his spacecraft but did not walk on it. There is no comfort to the “withered, sun-seared peach pit out my window,” he wrote in his memoir, Carrying the Fire. “Its invitation is monotonous and meant for geologists only.”
Humans are sensory beings, and the Moon is a place devoid of any familiar sensory experience. If you were to visit, you might experience conflicting feelings of deprivation and overwhelm. Every time you went outside—in a spacesuit, of course—and every time you went back indoors and took off your gear, the Moon would bowl you over. You would feel lonely, hot, freezing, terrified, ecstatic, superhuman, and tiny, in a matter of moments or maybe all at once. Its topography, its innards, its atmosphere—everything about the Moon is different.
Apollo 11 moonwalkers Neil Armstrong and Buzz Aldrin were the first human beings to experience selenic discomfort. Moon dust covered their spacesuits and boots, and it soon covered much of the inside of their Eagle lander, too. The pair were so annoyed by it that they slept in their helmets to avoid breathing in Moon all night.
On later missions, astronauts noticed the dust scratched their sun visors and damaged the seals on the rock boxes they toted home. Moon dust caused a form of hay fever, making astronauts’ eyes watery and itchy and their throats scratchy and sore. Unlike Earth dust, which is mostly made of organic material, Moon dust is all pulverized rock—and no water or wind exists to soften the dust grains’ edges. It was like breathing in sandpaper.
But the astronauts were lucky that this was nothing more than a nuisance. NASA scientists had warned the astronauts that Moon dust might be reactive in oxygen. Aldrin and Armstrong were told to be cautious about their contingency sample, a small scoop of Moon that Armstrong tucked into his pocket moments after stepping out of the Eagle.
After coming back inside, Aldrin and Armstrong watched the dust carefully as the Eagle cabin pressurized. If anything started to smolder, they were supposed to open the hatch and throw it out. But both men were completely coated in it.
“The stuff seemed to stick to things and stay there,” Aldrin said.4 “There was no hope of getting that off.” If anything was going to ignite, it would be their suits.
The dust turned out not to be reactive in oxygen, but it did smell that way. The Moon has an acrid aroma, like fireworks that have just gone off. That is how Aldrin described the scent in the capsule after he and Armstrong came back inside from their brief sojourn and took off their helmets. Armstrong described it as “the smell of wet ashes,” like a campsite at bedtime after you’ve doused the fire. Apollo 17 astronaut Harrison “Jack” Schmitt has called it the smell of gunpowder.
The Moon is constantly bombarded by sunlight and radiation from other stars and cosmic sources, and it’s pummeled by asteroids in a process called “gardening.” All this action tears apart atoms in the “regolith,” the technical term for Moon dust. Lunar regolith is about forty-three percent oxygen, so most of the atoms being shattered are oxygen atoms. The same is true of gunpowder. When it ignites, chemicals in the gunpowder release copious oxygen, further fueling the blast. What the astronauts smelled was the lingering aftermath of atoms being torn apart by tiny invisible bullets of radiation.
This is still a matter of scientific debate in part because the Moon rocks don’t have a smell anymore. When a scientist opens a bag with a Moon rock today, no matter how carefully it was chipped and packed up for distribution by NASA’s Lunar Sample Laboratory, there is no scent of the unknown. No one can say for sure why the smell fades once the rocks are exposed to humans, and to Earth.
On the Moon, after you got used to the smell of constant fireworks, you would notice the unceasing dryness. The Moon is a parched place, and you would dearly miss the omnipresence of water to which you have been accustomed your entire waking life. It would tease you every time you saw Earth. However familiar and beloved our continents and their mountains, Earth’s land does not dominate the planet’s features; from a distance, the water is what stands out, a blue beacon of serenity and warmth.
For most of human history, people believed that the Moon had oceans, too. Astronomers through the centuries believed the Moon’s dark spots were actually lunar seas. Moon-fixated scientists in the seventeenth and eighteenth centuries believed this so fully that the list of features on its face are all named as oceans, lakes, and bays.
The Sea of Tranquility, where Apollo 11 landed, was a real sea in the mind of Moon mapper Giovanni Battista Riccioli, the Jesuit priest who gave us the Moon’s modern nomenclature in 1651. Collectively, the dark spots are called maria, from the Latin for “seas.” In reality, as the Apollo Moon rocks taught us, the seas are vast plains of cooled lava.
While you would experience the Moon as a chalky, dry sea of emptiness, it does have water. Depending on what scientific instruments you believe, it has a whole lot. The trouble is that the water is locked up in the regolith as hydrated minerals, or may exist as ice that has been buried forever in craters that never see the light of day. Liquid water cannot exist on the Moon. With no atmosphere to keep water liquid, it would evaporate instantly, and its hydrogen would fly off into space. Any future Moon visitors hoping to access lunar water will have to be really talented chemists, skilled at liberating water from stone.
A “day” on the Moon, meaning one full rotation and one revolution around Earth, takes twenty-seven Earth days, seven hours, forty-three minutes, and twelve seconds. We call this a sidereal month, for the time it takes the Moon to orbit once around Earth and return to the same spot relative to the stars. But because the Earth-Moon system is rotating around the Sun, it actually takes a little longer for the Sun to return to the same place in the Moon’s sky.
The synodic month corresponds to one complete cycle of phases visible from Earth. From the point of view of the Moon, the synodic month marks the time between successive sunrises in the same spot on the Moon. No matter where you stand, this takes twenty-nine and a half Earth days.
Put another way, if you were standing on the Moon, it would take a full Earth month for the Sun to rise, set, and rise again. This also means daylight lasts for two weeks—and so does the night. You would need special equipment to survive this. Even some of the most sophisticated spacecraft we can build succumb to the frigid darkness of the lunar night, when the temperature drops to three hundred degrees below zero Fahrenheit.
Anyone who ever visits again will need a life-support system that allows them to survive the extreme temperatures on the Moon.
During the daytime, the Moon is a scorcher: The average daytime high temperature at the equator is two-hundred and forty-six degrees Fahrenheit. Within some deep craters, a few of which harbor the ice you might need for survival, the Sun never shines at all.
During Apollo 11, Armstrong and Aldrin had a hard time sleeping in their lander. The dust was annoying, but when they donned their Moon suits to escape it, they shivered with cold. The air-conditioning system in the suits was meant to keep them comfortable during the hot lunar day—inside the lander, it left them frigid. Anyone who ever visits again will need a life-support system that allows them to survive the extreme temperatures on the Moon.
The good news is you wouldn’t mind walking around in what is essentially a wearable house. The Moon’s gravity is one-sixth of Earth’s, which effectively means everything feels lighter. You would weigh just 16.6 percent of what you weigh on Earth, so a spacesuit wouldn’t be a burden. You might still have a hard time standing up, however; many of the Apollo astronauts fell flat on their faces after stepping onto the Moon’s surface.
Modern studies show why this happened. In a 2014 study in Toronto, Canada, volunteers spun around on a giant rotating arm to simulate different gravity forces. As they whirled and tried not to vomit, the volunteers were shown the letter p. They apparently read the letter as a p or a d, depending on which way they thought was up. They weren’t tilted in their centrifuge; it was the gravity change that confused them.
It turns out humans need to feel about fifteen percent of Earth’s gravitational force to sense which way is up. The Moon’s gravity is just a smidge higher than this, at about 16.6 percent of Earth’s. The low gravity and resulting disorientation might explain why it’s so hard to walk on the Moon.
From the book Our Moon: How Earth’s Celestial Companion Transformed the Planet, Guided Evolution, and Made Us Who We Are by Rebecca Boyle. Copyright © 2024by Rebecca B. Boyle. Published by Random House, an imprint and division of Penguin Random House LLC. All rights reserved.