Did Edmund Hillary Climb the Wrong Mountain

On May 29, 1953 Edmund Hillary (now Sir Edmund) from New Zealand along with Tenzing Norgay, a Nepalese Sherpa, stood on the summit of Mt. Everest and surveyed the "roof of the world." Thus these two men became the first to stand on top of the highest peak of the world. Or was it? Whether it was or not depends on the meaning of the word "highest."

From 1823-1830 George Everest (later Sir George) established an accurate triangulation survey for the mapping of India. An important part of this was the accurate measurement of 21.5 degrees of meridian arc from Cape Comorin to the Himalaya. The triangulation network reached within 100 miles of Mt. Everest then known as Peak XV. Later, from six stations on this chain, measurements were made to the peak; and in 1852 the final calculations were complete. Mt. Everest stood at 29,002 ft (8,840 m). This value remained as the official height until a survey made in 1952-54 from stations as close as 30 miles resulted in a height of 29,028 ft (8,848 m). It was important that the measurements be taken during the winter after the winds had blown the summit clear of the summer monsoon snows .

In May 1999 two GPS receivers, one at the summit and one at 26,000 ft (7,925 m), were used to obtain a new official height of 29,035 ft (8,850 m), an increase of seven feet. So Hillary climbed a mountain that was about 6.5 feet higher than he thought it was. Mt. Everest is rising at 3 to 5mm each year due to plate tectonics.

So far it looks like Hillary climbed the right mountain, but we can look at it another way. In Equador there is Mt. Chimborazo in the Andes just 1.5 degrees south of the Equator. Mt. Chimborazo is 20,702 ft (6,310 m) high. From about 15,400 ft (4,694 m) upward the mountain is covered with perpetual snow.

Now we come back to what is meant by the word "highest." Is it the distance above the geoid (sea level) or is it the distance to the center of mass of the earth hereafter to be called "earth center?" Since the advent of satellite geodesy and GPS, many measurements are referred to earth center. The GRS80 spheroid used for NAD83 is earth-centered, while the Clark 1866 spheroid used for NAD27 is not.

As it turns out, the distance from the geoid to earth center is much greater at Mt. Chimborazo than at Mt. Everest. This is much more than the difference in elevation of the two peaks. In table form it would look like this:

So, if we use "highest" as the distance to earth center, Mt. Chimborazo is 1.36 miles higher than Mt. Everest. However, I doubt if Hillary would be interested in climbing Mt. Chimborazo since the first to reach that summit was British mountaineer Edward Whymper in the year 1880. And anyway, I imagine that those who have made the arduous climb to the top of Mt. Everest would not take kindly to this definition of "highest." Still, the many climbers of Mt. Chimbrazo must feel some exhilaration in the fact that they once stood on the one piece of real estate that is the farthest from earth center.


Dr. Senne is principal in the firm of Elgin, Knowles & Senne, Inc., in Rolla, Missouri. The firm authors "Celestial Observation Handbook and Ephemeris" published and distributed by Sokkia Corporation.

*Earth center of mass to spheroidal surface.

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