Because the only totally correct representation
of the earth is a globe, cartographers have to distort
the sphere in order to print it on flat paper to produce
world maps. In the process scale, distance, area, or
a combination of these, are rendered imperfect.
Traditional world maps such as the Mercator often
exaggerate the scale towards the poles, giving an erroneous
picture of the relative sizes of different countries.
For example, Mercator maps show Greenland to be roughly
the same size as Africa, when, in reality, Africa is
actually fourteen times larger. Africa also looks considerably
smaller than Russia on a Mercator map, even though Africa
is actually 33% larger. However, generations of navigators
weren't bothered much by Mercator's misrepresentations,
since they cared most about longitude and latitude,
which the Mercator projection handles rather well.
In 1973, Arno Peters published the Peters
Projection map. This map preserves
equal area and retains a rectangular grid of latitude
and longitude. Thus all countries are the correct size
in relation to one another. On this projection it becomes
much easier to understand the relationships between
countries. However, a price is paid in the distortion
of shape - countries are progressively squashed towards
the poles and stretched across the equator. For those
who grew up with the Mercator map, the Peters projection
map appears to be stretched vertically, and Africa
suddenly looks huge.
A variety of social and religious groups argue that
since the Mercator map makes many countries appear smaller
than they really are, people seeing them may infer that
certain countries are innately more important than others.
This rhetoric has often escalated to the point where
the Mercator map is openly described as being "racist".
Many of these groups are working to address this perceived
problem by lobbying schools around the world to adopt
the Peters projection map in classrooms. This movement
is not without controversy, however, since educators,
well-aware of the Mercator map's deficiencies, were
already adopting maps based on other projections, some
of which are even more accurate than Peters's. Others
argue that Peters wasn't even the first person to devise
such a projection, since James Gall came up with the
same idea in 1855 (which is why some refer to it as
the Gall-Peters projection).