Eight thousand is a perfectly arbitrary number. Yet, no other number looms larger for mountain climbers. Fourteen mountain peaks stand taller than 8,000 meters (26,247 feet).



There could have been many more of these “eight-thousanders” if the French commission that established the length of the meter (in 1793) had made it just a bit shorter; there would be hardly any if they had made the meter longer.

The decision to make a meter equivalent to one ten-millionth of the distance between the equator and the North Pole left the world with fourteen 8K peaks. All of them are found in either the Karakoram or Himalayan mountain ranges of central Asia.

Fourteen is a number that pushes climbers to the point of obsession. It’s big enough that only the most ambitious consider climbing all of them, but small enough that doing so over a lifetime still seems possible. Even in the United States, a country where most people shun metric measurements, climbers dream of ascending the eight-thousanders. The “twenty-six-thousand, two-hundred-and-forty-seven-footers” hardly has the same ring.

However you measure them, the world’s tallest mountains are treacherous. They have towering blocks of ice—seracs—that can crush climbers in seconds. They are prone to tremendous avalanches of rock and snow that obliterate entire expeditions. And they are home to spider webs of ice crevasses that swallow humans whole. Even during the summer, average daytime temperatures are frigid. And, hurricane-force winds are common.

Then, of course, there is the lack of oxygen. At 5,000 meters (16,404 feet), the atmosphere contains about half as much oxygen as at sea level. By 6,000 meters (19,685 feet), the air is so thin that full acclimatization is no longer possible. No matter how fit, climbers begin to slowly suffocate. By 7,000 meters (22,966 feet), survival times plummet and lucid thought becomes difficult. By 8,000 meters—the so-called “death zone”—even the strongest climbers can survive for a few days at best.

The three most dangerous of the eight-thousanders—Annapurna, K2, and Nanga Parbat—claim the life of about one climber for every four who reach the top. The fatality rate for Annapurna, the most dangerous mountain in the world, is over 30 percent. Bottled oxygen and guided climbs have made Mount Everest much safer than it was decades ago, but the world’s tallest mountain still takes lives regularly. Nine people died on the mountain in 2013. Ten in 2012.

All this risk is for what, exactly? Reinhold Messner, the first person to climb all fourteen of the eight-thousanders, pointed to something he calls “overview” to explain the allure. “It is not the mountain but the view from the peak that suggests increased awareness,” he writes in the book Mountains from Space. “The person who stands on top of one comes back down with a new sense of the world.”

Messner risked everything for fleeting views from the top of the world, ascending many of the eight-thousanders solo and without the aid of bottled oxygen. It took him 16 years (1970–1986) to climb them all. Only 31 other people—give or take a few because the records of some climbers are considered controversial—have done it since.

While the summit of an eight-thousander may represent the ultimate view on Earth, satellites take Messner’s concept of overview to a whole new level. The summit of Mount Everest is about 8.8 kilometers (5.5 miles) above sea level. Most polar-orbiting satellites fly at an altitude of 705 kilometers (438 miles). So when viewed from space, the world’s tallest mountains become blotches of shadow, rock, and snow. Epic glaciers become narrow tongues of ice feeding glacial lakes that look like puddles. Deadly storms become mere tufts of cloud.

Ground photography of Mount Everest and the other tall peaks are ubiquitous, but the gallery that follows—a collection of imagery acquired by the Advanced Land Imager (ALI) on NASA’s EO-1 satellite—offers a less familiar perspective. The sensors on ALI looked directly down on the mountains, not from an oblique angle like a passenger on an airplane or an astronaut on the International Space Station might see them.

In some ways, this top-down view makes the images difficult for human eyes and brains to interpret. Scenes appear strangely flat. Separating a mountain’s summit from the ridge is challenging. Vast shadows obscure features in adjacent valleys, and opaque snows blanket everything.

Yet, in other ways, the view from directly above is the most valuable of all. Images like these make clear that the world’s tallest peaks are not isolated pyramids. Rather, they are part of long, sinuous ridges that stretch for such distances that it can be difficult to tell exactly where the summit lies.

With structures as massive and complex as mountains, distance provides clarity. Faults, suture points, glaciers all emerge—helping geologists piece together the story of how physical processes created these extraordinary mountains and continue to shape them today.

The geological story is one that began some 40 million years ago when the Indian subcontinent began a slow-motion collision with Asia, jamming the edges of the two continents into the massive ridges and valleys that make up the Himalaya and Karakoram today.

“If you want to understand how mountains form, these ranges offer a perfect laboratory. These are the youngest, most dramatic, and fastest uplifting mountains in the world,” said Michael Searle, a University of Oxford geologist and a veteran of dozens of expeditions to the Himalaya and Karakoram.

But it was journalist John McPhee who summed up the wonder of their geologic history when he wrote the Annals of the Former World, his Pulitzer prize-winning history of Earth’s geology: “The summit of Mount Everest is marine limestone,” he extolled. “This one fact is a treatise in itself on the movements of the surface of the Earth. If by some fiat, I had to restrict all this writing to one sentence; this is the one I would choose.”

In other words, when climbers reach the top of Mount Everest, they are not standing on hard igneous rocks produced by volcanoes. Rather, they are perched on softer rock formed by the skeletons of creatures that lived in a warm ocean off the northern coast of India tens of millions of years ago. Plate tectonics transformed ocean bottoms into the highest points on the planet. It’s just one of many bizarre realities of the eight-thousanders, mountains that will continue to fascinate scientists and obsess climbers for as long as they tower over everything else.

So, sit back and get ready to tour the world’s tallest peaks by satellite. No risk of avalanche. No threat of frostbite. No climbing boots required.