Continents sizes are very much distorted
Mercator projection is only true at the equator, by design. Anywhere else, sizes are false.Left : comparison between a Mercator map (grey) and a surface-preserving projection (red, the Robinson projection). Generally, Antarctica is omitted, for obvious reasons.
Why Mercator on Internet Maps? Laziness!
Mercator was chosen for online maps because of processing power lacking and laziness: it's easier to generate square map tiles. With Mercator, each map tile is square and has the same dimensions everywhere on the globe.
Ok but 2013 called, and said we have means to calculate projections in realtime, now.
Ok but how to proceed?
Solutions exists to produce surface-preserving maps :
- Realtime vector code libraries like D3js are able to reproject vector maps in realtime
- Base maps provided directly with a projection adequate to current coordinates and zoom by the map server (like most national mapping services).
- Cartographic tools with reprojection capabilities (nearly all of them, free or commercial).