eli5 if maps are inaccurate because we can’t project spheres on 2d planes. what happens if we actually decide to map the earth “by hand”?

Question

Like let’s say that we start on the cape of goodwill for example and follow the coast.

Represent each 1km with 1mm for example on our map (map size isn’t a problem just for the sake of the argument). Getting the directions of drawing off a compass exactly. And just walk around all the coasts of the world.

What type of map do we end up with in this hypothetical?

In: 5

Answer 1

Let’s ignore coasts and think about some extreme examples:

* You start at the North Pole, move south 1km, move east 1km, and move north 1km. On paper, you’ve made a U shape, but under ideal conditions, you’ve put yourself back at the North Pole after moving in a sort-of-triangle.

* Using this same south-east-north plan, you start near the South Pole. There is one particular area where your eastward movement completes a full circle, and you are again back at your starting point, having retraced the same path north that you took going south. [This video](https://www.youtube.com/watch?v=OOzzncDp2oE) goes into cases where your eastward movement is closer to the SP and results in multiple circles.

* There is another area about half a kilometer north where your eastward movement only completes a semicircle, and you end up over 2km away, technically on the other half of the world.

* There is yet another area further south where you also return to your starting point, but your eastward movement also crosses over your south/north path. However, this might not count since you are crossing the SP—any movement away from the SP is technically north, and any movement towards is technically south.

* Even at the equator, your south-east-north path doesn’t quite result in you being 1km away from your starting point, but you are much closer to your planned U-shape than at any other latitude.

Part of the problem is that you can never actually walk in a straight line on the surface of a globe. Your path curves into the globe by some amount. With Earth as large as it is, this curvature is almost impossible to feel.

Another part of the problem is that every east/west path that isn’t along the equator curves to the left or right. You’d probably notice this in the polar examples given above.