Peter's projection

Peters' projection.

Gall-Peters projection.

The Peters projection (named after Arno Peters), also called the Gall-Peters projection is a map projection that was first described in 1855 by James Gall, who in 1885 made it more widely known through an article in the Scottish Geographical Magazine.

The Peters projection is equivalent, that is to say that it preserves the proportion between the areas of the different zones of the Earth. This is its main difference with the Mercator projection, the most widely used and currently, which preserves the angles but not the areas.

The Peters projection tries to flee from the Eurocentric image of the world, since the Mercator projection grants great space to the lands closest to the poles and makes it look like northern Europe, Russia and Canada, much more bigger than they really are. Also, it is capable of representing high latitudes to the very north and south poles, something mathematically impossible on the Mercator projection. Minor distortions are found in the mid-latitudes, where most of the population lives.

Mathematical definition

x=Rλ λ and=2Rwithout φ φ {displaystyle {begin{aligned}x fake=Rlambda \y fake=2Rsin varphi end{aligned}}}}}}

where:

• λ is the length from the central meridian (in radian),
• φ is latitude
• R is the radius of the dial taken as a model, of the globe.

Therefore the sphere is projected onto a vertical cylinder, and the cylinder is stretched to twice its length. The stretch factor in this case is 2.

The various variants of the equidistant cylindrical projection differ only in the ratio of the vertical to the horizontal axis. This proportion determines the standard parallel of the projection, that is, the one in which there is no distortion and the distances coincide with the specified scale. The standard Gall-Peters parallels are 45°N and 45°S.