HOW HIGH IS
HIGH?
Everybody knows that Mount Everest
is the world’s highest mountain. However, a recent scientific expedition sponsored by Boston’s Museum of Science and
The National Geographic Society has
thrown the mountain’s exact height into
doubt.
Remarkably, Radhunath Sikdar, working for the Great Trignometrical Survey
of India in 1852, measured the angle of a
high mountain in the Himalaya with a 24inch theodolite from more than 100 miles
away. Basing calculations on these measurements, the mountain was determined
to be 29,002 feet (8,840 m.) in elevation,
the world’s highest. Nine years later, the
mountain was named after Sir George
Everest, a British surveyor general.
A 1954 Indian expedition surveyed
Mount Everest again, and determined that
its elevation was 29,028 feet (8,848 m.).
This elevation has been accepted worldwide for 44 years as the official elevation.
This survey, however, again used a the-
odolite, an optical surveying instrument,
which is now largely obsolete.
Unlike modern geographic positioning systems (GPS), light refraction and
gravitational pull affected theodolites’ accuracy. Since the Himalayas are such
massive mountains, their total mass creates increased gravitational pull that can
affect the leveling of surveying instruments.
The most recent expedition, however,
was designed entirely to make the most
modern scientific measurements possible,
including Mount Everest’s elevation. The
expedition reached the mountain’s summit on May 20.
According to a Sept. article on The Mountain
Zone
website
(www.mountainzone.com), one of the
first duties of the group was to bolt a
Trimble 4800 GPS unit to a rock as near
the summit as possible to record geographic measurements.
Because snow and ice cover the actual
summit, the highest rock outcrop is Barry
Bishop Ledge, a few feet shy of the crest.
This rock ledge, named for renowned
geographer and mountaineer Barry
Bishop, was visible in a famous 1963 photograph taken by Bishop showing the
American flag. As a footnote, Barry Bishop
went on to become a vice president of the
National Geographic Society and recently
died in an auto accident.
After two weeks of data gathering, the
expedition’s GPS unit and its data were
retrieved from Mount Everest by another
expedition.
The GPS uses satellite triangulation to
calculate its x, y and z (horizontal and
© 2000 maps.com
vertical) positions. These data from Mount
Everest were entered into a mathematical
model, which accounted for the ellipsoidal shape of the earth.
Ice and snow at the crest of Mount
Everest change constantly through accretion and ablation (accumulation and removal). For this reason alone, the actual
elevation of the summit may change a
few feet or meters each year.
The newest calculation of Mount Everest’s
height is 28,998 (8,838 m.). Whether this
number is the final word is yet to be seen.
The scientific community is continuing to
debate the issue, although we now know
that the mountain’s actual elevation will
vary slightly from year to year.
Mount Everest’s nearest rival is another Himalayan mountain, K2, located
about 875 miles (1,408 km.) to the northwest in the Karakorum range. This mountain, although never measured using the
newest GPS techniques, has a currently
accepted elevation of 28,250 feet (8,616
m.).
So despite the lowering of Mount
Everest’s elevation through recent measurements, it remains the highest and
most revered mountain in the world. All
who seek to conquer Mount Everest find
an awesome opponent which has claimed
143 mountain climbers’ lives since Sir
Edmund Hillary and sherpa Tenzing
Norgay first climbed it in 1953
And that is Geography in the News, September 28, 1998.
(The author is a Professor of Geography at
Appalachian State University, Boone, NC.
Geographers Baker Perry and Jeffrey Scott
provided research assistance.) #450