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Geoid undulation map, the degree of fluctuation has been magnified 10,000 times. Photo: Ince, E. S. et al. (2019) Earth System Science Data, 11, pp. Mount Qomolangma is the highest "elevation" peak on earth, and its height is calculated relative to the sea level. However, many Earth-like planets do not have oceans. What is the standard for calculating the height of their peaks? There are two new criteria: the height from the foot of the mountain to the top of the mountain, and the distance of the peak from the core of the planet. According to these two standards, the highest mountain on earth is not Mount Qomolangma, but...

As we all know, the highest mountain on earth is Mount Qomolangma. Just like knowing that there are eight planets in the solar system, or that the blue whale is the largest animal, this is one of the facts we have known since childhood.

However, this fact is not that simple. As the highest peak in the world, Mount Qomolangma has certain conditions-it is the highest mountain in "altitude", and the height of Mount Qomolangma is calculated relative to sea level. This standard may be practical on Earth, but what about other planets? You know, Venus, Mercury, Mars and other terrestrial planets have no sea, so there is no such thing as the height relative to the sea level. Without the concept of altitude, how can the peaks on these planets measure their heights? Under these new standards, is the highest mountain on earth still Mount Qomolangma?

How does elevation measure the uneven surface of the earth, and there are many areas covered by water bodies. If you want to know the exact height of a mountain peak, you must first choose a consistent datum. For this reason, surveying and mapping defines a concept called "Geoid", which is a gravitational equipotential surface, that is, the plumb line at any point on the leveling surface is perpendicular to the plane, and gravity does not do work when moving an object along that plane-so water does not flow on this surface.

In theory, there can be an infinite number of gravity equipotential surfaces on the earth's surface, but in surveying and mapping, the surface that coincides with the mean sea level (mean sea level) is generally selected as the geoid. The altitude of the mountain peak as we know it refers to the height of the mountain peak relative to the geoid.

The figures in the picture show that: 1. Sea level; 2. The ellipsoid of the earth is decent; 3. Local plumb line; 4. Continental surface; 5. Geoid (photo: Wikipedia) in order to measure the altitude of a mountain, it usually requires a plane to fly back and forth around the peak along a series of parallel lines to measure the gravity distribution at the top of the mountain. From these measurements, coupled with GPS readings, scientists can now get a very accurate altitude. According to the latest measurements released in December 2020, Mount Qomolangma is 8848.86 meters above sea level, about one meter higher than previously recognized height, which is indeed the highest elevation on earth.

However, the altitude record of Mount Qomolangma is really cheap, and the Qinghai-Tibet Plateau itself is the highest on average on earth. In this place, the surface is usually a little bulging, and the altitude is a huge number. Just because Mount Qomolangma is the highest above sea level does not mean that the body of this mountain is the highest. If we measure the height of the mountain itself, that is, the height of the top of the mountain relative to the foot of the mountain, which is the highest peak on earth?

The answer is the Mauna Kea volcano (Mauna Kea) in Hawaii. This is a dormant volcano, because of its dry environment and stable air flow, it is suitable for astronomical observation. Since the road was built in 1964, 13 telescopes funded by 11 countries have been built on the mountain. Although Mount Nakea is only 4205 meters above sea level, less than half of Mount Qomolangma, most of the volcano's mass is hidden below sea level. According to the US Geological Survey (United States Geological Survey), the total height of Mount Nakea can reach 10,211 meters from the foot of the sea, far exceeding the height of Mount Qomolangma.

The colored part is the protruding part of Penakaia volcano, and the gray part is the part of the volcano below sea level. Photo: Wikipedia) in addition to measuring the height of the mountain body, on planets without oceans, there is another measure of the height of the mountain: the distance of the peak from the planet's core. As far as the earth is concerned, affected by rotation, the earth is not a perfect sphere, but a slight uplift along the equator. According to NASA's Goddard Space Flight Center, the polar radius of the earth is about 6356 kilometers, while the equatorial radius is about 6378 kilometers, a difference of about 22 kilometers. This gap has exceeded the elevation of any mountain on earth, which means that peaks near the equator are naturally farther from the center of the earth.

The farthest peak from the center of the earth is Mount Mount Chimborazo, which is located at about 1 °south latitude. The mountain is located in the Andes of Ecuador, although it is not even the highest peak in the Andes in terms of elevation, but its location near the equator makes it the most prominent place on earth: Mount Chimborazo is about 6384 kilometers from the center of the earth, about 2 kilometers farther than Mount Qomolangma to the center of the earth.

Mount Chimborazo (Photo: Eduardo Navas) whether you think the tallest mountain on earth is Mount Qomolangma, Mount Maunakaia, or Mount Chimborazo, they are not as high as Mount Olympus Mons on Mars, the tallest known volcano in the solar system. According to NASA, the mountain is about 25 kilometers high, almost three times the size of Mount Qomolangma, and its bottom diameter is about 600 kilometers, equivalent to the distance from San Francisco to Los Angeles.

In the asteroid belt between the orbits of Mars and Jupiter, there is an asteroid Vesta and a crater called Rheasilvia. According to NASA's Jet Propulsion Laboratory, there is a peak at the center of the crater, which scientists believe may be between 20 and 25 kilometers high, meaning it may also be one of the highest mountains in the solar system.

Mount Qomolangma has become a mecca for mountain climbers, and thousands of people have climbed the highest mountain on earth. I wonder if in the distant future, when mankind enters the space age, will mountain climbers turn their attention to these peaks on Mars and Vesta?

Reference link:

Https://www.livescience.com/tallest-mountain-on-earth

This article comes from the official account of Wechat: global Science (ID:huanqiukexue), written by Bai Defan, revised by Wang Yu

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