prize7-5, Exercise 1: Greenland on a Mercator map

Model answer (check the details):

Why Greenland looks large: on a Mercator map the east-west scale grows with distance from the equator, and to keep shapes right locally the north-south scale grows with it. Near the poles the scale becomes very large, so high-latitude areas are inflated. Greenland, far north, looks about as large as Africa, though Africa is many times larger.

What the design was for: Mercator wanted a chart on which a line of constant compass bearing is a straight line, so a navigator could draw a course with a ruler and read off the bearing. Keeping bearings and local shape right required the stretching.

Conclusion: the map does its intended job well and is poor for comparing sizes. The mistake is in using it for a purpose it was not designed for.