The Mercator Puzzle reminds you how deceptive maps can be

The Earth is round, and maps are flat. While we have may mapped nearly every inch of our world, figuring out how to translate that information from three dimensions to two remains a problem.

Most maps use the Mercator projection, which distorts the size of countries closer to the poles. An online puzzle reveals just how deceptive—or at least confusing—these maps can be about the actual size of different countries on Earth, by asking you to match the outlines of 15 landmasses to the appropriate country. The trick is that as you move these outlines north and south, they grow dramatically larger and smaller.

If you've never realized that seemingly massive Greenland is actually smaller than Australia, go ahead—blow your mind. The Mercator Puzzle is free to play in browsers.

Notable Replies

  1. It's right at the end.

    I've learned that it is never a waste of time to re-watch any clip from "West Wing"!

  2. SamSam says:

    This here is a truly excellent tool for both exploring loads of different projections, but also exploring how each projection itself is a choice that can be displayed any number of ways, depending on where you put the poles and where you center it:

    https://www.jasondavies.com/maps/transition/

    For best results, I find the animation annoying: hit the Pause button, and and move the map around by dragging it.

    It's amazing both how bizarre certain maps can make places look, but also how right they can be when dealing with small areas and simply ignoring all the distorted countries elsewhere.

  3. renke says:

    The Bonne projection! I <3 the planet :smile:

    Finland and Saudi Arabia. Took me extremely long to recognize the outlines.

  4. Most maps use the Mercator projection,

    Umm, [citation needed].

    In my childhood, most schoolroom wall maps used the Mercator projection, but people have gotten a whole lot smarter about maps over the last half-century - and the area inequalities of the Mercator have been the subject of articles like this one for at least four decades. (I know because I wrote one myself almost 40 years ago.)

    Hmm. I see the NYT was even editorializing about it in the '40s.

    That said, the problem isn't that the Mercator is 'deceptive' - The problem is that the Mercator is the wrong projection to use if you want to compare land areas.

    You'd want some sort of equal-area projection for that. There are plenty to pick from.

    But comparing areas isn't the only purpose that maps have. The Mercator projection, despite its well-known flaws (which were pointed out by the inventor himself), is a useful map for ocean navigation, because any straight line drawn on it is a rhumb line, a line of constant compass bearing.

    That's not the most efficient point-to-point course, but it's one of the easiest to navigate: just keep the ship constantly on the same compass heading.

    Also, the Mercator preserves angular relations locally, so you can plot local sightings by compass bearing.

    Both of those things are handy for sailors, but are mostly irrelevant to schoolchildren.

    As the article says, all flat-map projections necessarily distort some aspect of a spheroidal surface. There are many different kinds of projections, each with its own trade-offs, used for many different purposes.

    Learn which projections are which, and use the projection suitable to your purpose, and you won't have to complain any more about maps "deceiving" you.

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