Why are world maps cut off?

Upvote:2

Each map will be designed to serve a specific purpose, which may lead to comprises in how it is rendered.

A map that concentrates on political details (borders), doesn't really (other than possibly the coastline) need areas that don't have political borders.

The Northern Hemisphere has a larger land mass, where more details are needed (paper space), so the area south of the Antarctica coastline (which has no details to show) is often simply left out.

A pure shipping lane may may even leave out northern areas, so that more space is available for details which the designer wants to concentrate on.

A map of the world (for navigation purposes i.e. flat) the placement within the planet (Mercator projection) will show those areas that are otherwise not needed. The size of each area is, however, distorted.

  • Greenland is shown here as being larger than Africa

The Peters Projection attempts to correct the distortion of the Mercator projection, giving a more realistic size relation. In width, the maximum northern/southern are still distorted giving an incorrect impression of its shape. For navigation, however, thus type of map is usefull. Distances are more realisticly displayed.

A map that concentrates on the shape and size of the land masses, may look completely different.

  • Greenland size is being shown here realisticly (i.e. smaller than Africa)

For navigation purposes this map would not be used.

So when selecting a map, it is important to know for what porpose the map was intended for.

Sources:

Upvote:2

Projecting from a (roughly) spherical object onto a flat plane, is a messy business. There are many projections, each with their pros and cons.

In particular any map that tries to keep north/south as up/down and west/east as left/right across the map is inevitably going to badly distort the polar regions. Some projections (such as the mercator projection) theoretically have infinite hight, so a cut must be made somewhere. For other projections cutting off the map is purely a practical and artistic choice.

On a political map, there is some sense in including the northern coastlines of the northern countries, even if they are badly distorted to show clearly which bit of land belongs to this country.

Antarctica on the other hand will always be horribly distorted on a rectangular map and doesn't really have any meaningful political borders. Some countries do have claims and mutually recognize each others claims, but other countries with a presence in Antarctica don't.

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