Thursday, May 27, 2010

Stunned again

Mercator projection

I hate it when smart people mess with my reality. They steal my knowledge, my justified true belief.

The mercator map is one that we are all familiar with. Every school I ever went to had it displayed somewhere, if only in textbooks. I knew it as a globe, flattened.  You don't have to spin a mercator projection to see where another continent or country is. In one eyefull, you see the globe.

Of course, growing up in Argentina, our geography classes taught us something a bit different. It looked like this:
 © 1979 Stuart McArthur

 A McArthur's corrective map is nothing more than a reversed map. And, considering we were living in Argentina, it only made sense that OUR country was on the top half of the page... 

But today, along come James Gall and Arno Peters. 
They say a flat map needs to be projected with this in mind:
The projection is conventionally defined as:
x = \frac{R\pi\lambda}{180^\circ\sqrt{2}} = \frac{R\pi\lambda\cos 
y = R \sqrt{2} \sin \varphi = \frac{R\sin \varphi}{\cos 45^\circ}
where λ is the longitude from the central meridian in degrees, φ is the latitude, and R is the radius of the globe used as the model of the earth for projection. For longitude given in radians, remove the π/180° factors.

In other words, it needs to look like this:

Gall-Peters Projection
from NASA)
It looks like the world has a long face...
Hmmm, maybe it does. 

The Gall-Peters projection is noted for being 'correct' in depicting the continents in correct proportions. You noticed (didn't you?) that Greenland now is correctly shown - since it is not larger than Africa, it can NOT be shown larger than Africa (look again at the Mercator projection).

Ok, Gall-Peters win. And I am sad. Guess my face is long...
The McArthur Map is available world-wide from ODT, Inc. (1-800-736-1293; Fax: 413-549-3503; E-mail: Also available in Australia from McArthur Maps, 208 Queens Parade, North Fitzroy, 3068, Australia; Phone: 0011-613-9482-1055; Email:
Check out their website/store site. I dare you not to want to buy something! 


Remington said...

Very interesting....

altadenahiker said...

How do you compare the accuracy of this to the Goode map?

Sugar the Golden Retriever said...

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Brenda's Arizona said...

AH, we used Goode maps forever in college. I loved the 'orange peel' effect it had on me. We all lugged around Goode Atlases. I think they were considered VERY accurate, and still are held in high regard.