The image below is a picture of the tallest mountain in the world. Do you know which is it?
If you answered Mount Everest you are correct. This mountain is over 29,029 feet high above sea level and has a lot of name recognition. But let me ask the above question in a different way. When measured from the center of the Earth, which is the tallest mountain in the world? Or alternatively, the summit of which mountain is closest to outer space? Surprisingly the answer is not “Everest” but rather the mountain in the picture below. Do you know its name?
This is a volcano in Ecuador called Chimborazo and it is 20, 564 feet tall when measured from sea level; an altitude way below that of Everest. However, when measured from the center of the Earth, Chimborazo is 1-2 miles taller than Everest and therefore its summit is also closer to outer space. In fact, when the height of a mountain is measured in this manner, Everest is not even in the list of the 20 highest mountains!
How can this be?
We need to remember that our experience can fool us. What can be more natural than to measure the height of a mountain from sea level to its summit? And the summit of the mountain thus found to be the highest must also be the closest point in the world to outer space, right?
If we were living in a flat Earth or on a planet that does not rotate, that would indeed be the case, but the Earth is not a perfect sphere. Due to the Earth’s rotation, the land and the sea around the equator bulge outward. Someone standing at sea level on the Earth’s poles is about 13 miles closer to the center of the Earth than someone standing at sea level on the equator. Because Chimborazo is located 1 degree south of the equator, it sits on top of this bulge, whereas Everest which is 28 degrees north of the equator is closer to the Earth’s center.
Considering this, one interesting question is: what about the death zone?
The death zone is found in high mountains above an elevation of 26,000 feet above sea level. At this altitude the abundance of oxygen is only 1/3 of that found at sea level, and the bodies of most people are incapable of adapting effectively. The death zone is one of the reasons Everest is so hard to climb, and also why the route to the top in this area of the mountain is littered with the bodies of dead climbers. One would expect that if the summit of Chimborazo is closer to outer space than the summit of Everest, then it should also have a death zone. As it turns out this is not the case because the Earth’s atmosphere also bulges at the equator. As a result of this, the summit of Chimborazo is safely below the death zone and, unlike what happens in Everest, the bodies of most people can function in the thin atmosphere of the summit if allowed the time for adaptation to high altitudes.
The foregoing illustrates the effect that small differences can have on some seemingly conventional measurements when these differences are taken into account over planetary scales. In terms of distance, the 13 miles that our planet bulges around the equator represents but a tiny fraction of the 3,959 miles comprising the Earth’s radius, and yet, this is enough to make the summit of Chimborazo the highest point on our planet!
Everest from base camp
Photo credit: Rupert Taylor-Price / Foter.com / CC BY
Photo credit: apgwhite / Foter.com / CC BY-NC-ND