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Where is Germany? According to the maps we used in elementary school Geography class, it’s in the middle of Europe. But it’s not. It’s near the northwest corner.
Greenland and Africa are
roughly the same
size, right? Wrong. Africa
is actually fourteen
times the size of Greenland. That’s
shown accurately by the map on the left, but not the one on the right. The size distortion, and other inaccuracies,
are characteristic of the Mercator Projection, the one on the right. It’s the one most of us saw on the walls of
our elementary school. A “projection” in the
field of cartography is
the method of representing the content of the Earth’s spherical surface
on a
flat surface. However, no flat map can
represent all aspects of a spherical surface correctly, so there are
many
projections; each one represents selected aspects accurately or
conveniently to
serve particular needs. Other things
are, unavoidably, distorted. Notice how
much smaller Greenland, Canada and Alaska are, on the left-hand map. That one shows relative sizes accurately. In 1569, Gerardus Mercator
published a projection that makes lines of longitude and latitude
straight and
mutually orthogonal, thereby making it easier for the European mariners
of his
time to use celestial navigation when crossing large oceans. His projection also shows shapes accurately,
but not sizes or relative positions except near the equator. Many schools have switched to
other
projections in recent years, but Mercator maps are still used widely by
mariners and airline pilots today.
A projection promoted by
Dr.
Arno Peters, who claims to have devised it (more about that in a
footnote)
shows both size and position accurately, though not shape:
Any flat projection of a spherical surface
must choose between size and shape accuracy.
The most recent objection regarding the Mercator projection is that it distorts in a way that undersizes the “third world” countries. The claim is that since we so often judge things based on size, Mercator devalues those countries. Even placing the northern hemisphere at the top of the map makes that hemisphere seem more important. (Some advocates have actually suggested reversing the positions.) The Peters projection has
stirred strong controversy*,
much of it fueled by its claimed developer, Peters, himself. However, it is un likely to come into wide
use, particularly because projections have been developed that strike a balance among the accurate
representations of size, shape and position.
One example is the
Robinson projection shown above. Of
course, it has its shortcomings: Notice
the horizontal stretching of the
Earth’s shape, and the fact that most lines of latitude and longitude
do not
cross at right angles. So you have the choice: Do you want accurate shape, size, location,
or something else? Whatever you want,
there’s now a projection that will supply it. But if you want it all,
use a globe. * More
than a century before Peters published his “new” projection, English
clergyman
James Gall had published the same projection in the Scottish
Geographical Magazine. In
an interview, Dr. Peters claimed that he had never heard of the Gall
projection
prior to inventing his. Nonetheless, many refer to the Peters
projection as the
Gall-Peters projection. The material in this
article
is based on information from sources including George Simons
International,
www.about.com, and others. W.
A. Shapiro
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