# The highest mountain

## Frederic Friedel on getting the earth back to scale

“Which is the tallest mountain in the world?” seven-year-old Enders asked his grandmother recently. Ingrid has studied geography at university and ought to know. “It’s Mount Everest,” she told him. “It is close to 9000 meters high and was first scaled…” — “No,” said Enders, “it’s a volcano on Hawaii!”

“Mauna Kea?” asked Ingrid, “That’s only 4000 meters high.” But Enders insisted: “It’s the tallest mountain.” Suddenly we realized what he was getting at: it is taller from its base, which is at the bottom of the Pacific Ocean.

Mount Everest is 8,850 meters (29,035 feet) tall and reaches what is generally considered the highest altitude on earth. Mauna Kea is a dormant volcano that rose out of the ocean about a million years ago, to a height of 4,207 m (13,803 ft) on the island of Hawaii. It is flat and gently sloping, while Everest is steep and treacherous.

You must remember that the numbers given above represent the heights of the peaks above sea level. But most of the Mauna Kea is under water, and when the measurement is taken from its oceanic base the volcano is over 10,000 m tall, making it the tallest mountain in the world. That’s what smarty-pants Enders was talking about — he had picked it up from someone in his school.

Now let us consider something different: which is the highest point on earth. To put it more clearly: which point of the land mass of Earth is farthest from the middle of the planet? Clearly it’s the peak of Mount Everest, you say? The dinner-table sized surface 8,850 meters above sea level? Wrong. Think about it — I’ll explain at the end of this article.

But first part two of today’s discourse. I was recently thinking of getting the grandkids a 3D topographical relief globe, one that lets them get a feel for what the surface of the earth is like. I was thinking something like the one by Etsy on the left below [click to enlarge], not the one on the right, which, shall we say, is slightly exaggerated.

Actually even the Etsy globe is grossly exaggerated. Just consider: the highest point of our planet, Everest, protrudes 8.8 km (just over five miles), and the lowest point, the Mariana Trench in the Pacific, is about 11 km deep. Earth’s diameter is 12,735 kilometres, so shrinking it down to a 20 cm globe would make the 20 km difference shrink to a third of a millimetre. And these highest and lowest locations are not even next to or close to each other. So if you ran your palm over an accurate topographical globe it would feel smooth as a bowling ball. I could elaborate further on this, but Neil deGrasse Tyson does a great job in the following video (from 2 min 40s to 4 min 55s).

Incidentally, what would the vast oceans of Earth feel like when it is shrunk to cue-ball size? “I think this thing is slightly wet,” the giant who is handling it would say.

So let’s add the atmosphere of the earth to our model. How does that look on a sitting-room scale? The atmosphere consists of the Troposphere (0 to 12 km up), the Stratosphere (12 to 50 km), the Mesosphere, Thermosphere, and the Exosphere, which starts at 700 km. The Kármán line, about 100 km up, defines the boundary between Earth’s atmosphere and Space — the altitude at which the atmosphere is too thin to support aeronautical flight.

This is what the atmosphere of earth looks like in proper scale:

Mind you, the area where human beings can survive, between sea level and 8000 meters—the summit of Everest — is represented by the light blue line in the graphic above (thankfully provided by Oliver Walkhoff). Actually it’s where humans can barely survive: normal people tend to feel considerable discomfort above 2500 meters and to die at 8000 — except for Reinhold Messner, who in 1980 scaled Mount Everest alone and without supplemental oxygen. So our habitable zone is as depicted in the inset. Hard to believe.

Anyway it is sobering to realize that our place on the surface of the earth extends from the very thin, hardly visible dark area below the light blue line, and around one third the width of the light blue line itself. And remember we feel comfortable only on around ten percent of that area: 70% of the earth’s surface is ocean, 10% is too cold and 10% too hot for humans.

So back to the puzzle: which is the highest point on the earth’s surface, i.e. which is furthest from the centre of the earth, and closest to the moon or the next star? It is not the summit of Everest, nor the top of Mauna Kea, which is much closer to the earth’s centre and further away from Space. The correct answer is (ta-dum!) Mount Chimborazo, located in Ecuador.

Look carefully: see that little red dot on the summit (picture by Eduardo Navas Costale for Wiki — click to enlarge). If you scale this peak, which is just 6,263 m (20,548 ft) high, you are further from the centre of the earth and closer to Space and to the moon than anywhere else on Earth. How so?

Well, the earth is not a perfect sphere. Due to its rotation — since its formation it has spun around on its axis around 1.7 trillion times — it has become an oblate spheroid. In fact it was Isaac Newton who first proposed that Earth was not perfectly round, but slightly squashed at the poles and bulging at the equator. He was not able to measure this, but was correct: the distance from the centre of the earth to sea level is around 21 kilometres (13 miles) greater at the equator than at the poles. This means that if you are in a boat on equator you are 13 miles further from the centre of the earth than in a boat near the North Pole.

Chimborazo is located just one degree away from the equator, and its peak is 6,384.4 km (3,967 miles) away from Earth’s centre. Everest’s peak is 6,382.6 km away, and so standing on the top of Chimborazo (the red dot on the picture above) you are 1.8 km further from the centre of the earth — and 1.8 km closer to the moon — than if you are standing on the peak of Everest. You can watch this video which does a nice graphic description.

Incidentally, there are eight more peaks that are closer to the moon than Everest. One of them is Kilimanjaro: its peak is exactly one mile further from the centre of the earth than the summit of Everest. Above is a picture from this video of an amateur ascent to the summit of Kilimanjaro — before, I assume, they opened a Starbucks up there. If you want to do the same make sure you choose the right peak (see the Monty Python sketch).

One more thing: you looking for really big and really tall? Then we should go to Mars, a planet that is half the size of Earth, and the second-smallest in the Solar System. On it we find something truly humongous.

Olympus Mons is a shield volcano, the tallest planetary mountain in the Solar System. It is 22 km (13.6 miles or 72,000 ft) in height, about two and a half times taller than Mount Everest. At its base it occupies an area almost the size of France. Everest, Schmeverest, now that is one truly big mountain.

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