Cropping the Mercator Projection

Mercator_projection_SW

The Mercator projection is the map people love to hate. The West Wing humorously laid out the case in one of their “big block of cheese” episodes, and the complaints generally fall on the issue of distortion: things far from the equator are stretched more than things near the equator. Greenland appears to be the same size as Africa, but is actually about 14 times smaller.

One thing that people generally don’t comment on is the fact that a Mercator world map never actually shows the entire world. It’s not uncommon, like the image above, to cut off the northern latitudes at 80 or 82 degrees, leaving off the northernmost parts of Canada, Russia, and Greenland, and to slice Antarctica at a point that just barely leaves in all the coastline. Even Google Maps – yes, Google Maps, like most online mapping services, uses a form of Mercator – cuts off at right around 85 degrees (although the precise choice is for a secondary cool reason I’ll mention below).

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