Mt. Everest Is Not the Tallest Mountain on Earth

Mt. Everest

Everest

Everyone knows that Mt. Everest (8,848 m / 29,029 ft) is the tallest mountain on Earth. But maybe it's not. Known as Sagarmatha in Nepal and Chomolungma in Tibet, Everest was first seriously accurately measured in the 1850's, when it was known by the glorious name of Peak XV. But what exactly was measured? It is 8,848 m from what to what? The top measurement spot is the rock head at the peak, plus about a meter of its permanent snow cap. But what about the bottom spot?

Establishing the "base" of a mountain is a bit more vague, because some mountains lie upon a high plateau, while others stand atop lowlands, and some even slope deep into an ocean. Therefore, most measurements determine how high a mountain rises above Sea Level, which is generally a stable standard, not counting lunar tides, storm surges, tsunamis, and belly flops by youngsters who were warned not to do that with other people around. So, Everest is 8.848 km above Sea Level.

Mauna Kea

But some people feel that Sea Level is not an accurate indicator of where a mountain begins, since it does include many constant changes. Mauna Kea, an inactive volcano in Hawaii, is only 4,205 m (13,796 ft) above Sea Level. Everest scoffs at its puny height. However, Mauna Kea's base is not at Sea Level, but actually extends beneath the Pacific Ocean for another 6,000 m (19,700 ft) below the surface. This would make it a total of 10,210 m (33,500 ft) high, base-to-peak, which is way more than Everest's 5,200 (17,060 ft). Who's scoffing now, Sagarmatha?

So Mauna Kea must be the tallest mountain in the world. Well, no, it is not.

Chimborazo

Sea Level is inconsistent, and the base of a a mountain is vague. The only consistent, accurate measurement on Earth is actually inside Earth -- the location of the Center of the Earth (CoE). Therefore, we want to know which mountain's peak is the furthest away from CoE.

Everest's peak is 6,382.3 km (3,966 mi) from CoE. That sounds like a lot. In fact, it's about the same distance as flying between Berlin and New York City -- coincidentally, a trip you would have to take if you wanted to eat a  Berliner Pfannkuche at Olympiastadion and a Ray's pizza at Yankee Stadium within the same day.

Even if we measure all mountains in the same manner, and since CoE is in the same location for every mountain, wouldn't Mt. Everest still be the highest mountain ? No. That is why you are reading a blog entry about this, after all.

The Earth is not a perfect sphere. It is an oblate spheroid -- which is just a silly name for a flattened sphere. The Earth is a sphere that is flattened at its poles, and therefore bulges at its equator. It does this because it is rotating, and centrifugal force is pushing outwards at the Equator. Because of this Equatorial Bulge, the Earth's diameter from pole-to-pole through CoE is 12,713.56 km (7,899.84 mi), and measures 12,756.27 km (7,926.38 mi) across the equatorial plane -- a difference of 42.77 km (26.58 mi).    

This means that an object at the North Pole -- let's just say a fat guy in a red suit, just to give an example -- would be about 21.36 km (13.27 mi) closer to CoE than a ship on the Equator that's headed for Skull Island. And we are assuming that the ship is at Sea Level, for reasons we won't divulge.

After all this talk about oblate spheroids and bulges, I can tell you that there is a mountain whose peak is further from CoE than Mt. Everest or Mauna Kea: Mt. Chimborazo in Ecuador is only 6,267 m (20,548 ft) above Sea Level. However, because of its proximity to the Equator, it is 6,384.4 km (3,964 mi) from CoE -- approximately 1,811 m (5,942 ft) more (higher?) than Everest. So, it seems that Chimborazo is the Earth mountain whose peak is closest to outer space.