I remember being told this in high school and being totally confused. My teacher told us that a standard map, or even a globe, is inaccurate. She explained why but I didn’t understand. Why is this?
In: Technology
The globe is *technically* inaccurate, because the earth is a slight ellipsoid rather than a sphere, and chances are the globe doesn’t take that into account, but the error is trivial for anything a regular globe is used for – also far far less than the inaccuracies of that result from measuring tolerances.
The flat maps are inaccurate as you cannot project a curved surface onto a flat one without losing integrity in some combination of size, shape, direction or distance, with the errors becoming more significant the bigger the area shown on the map. For anything in the range <50 miles square the errors are trivial outside of extremely high precision applications, and if you’re doing those you know all about this issue. There are a lot of different projection methods that each preserve some of these qualities better than others, basically you have to trade off the properties you don’t care about as much for those that you do.
A globe is definitely accurate.
The standard maps are inaccurate because the world is round, and maps are flat. There’s no way to project a spherical map on a flat surface without stretching or tearing parts of the map. In the former case you get maps like the [Mercator projection](https://en.wikipedia.org/wiki/Mercator_projection) which makes areas closer to the poles huge, and in the latter case you get odd things like [this](https://en.wikipedia.org/wiki/Goode_homolosine_projection).
Imagine you have a balloon and you draw a bunch of same sized dots on it, then you cut a line to define one edge of the balloon and and try to lay it flat like a map. Obviously, you’re going to have trouble simply making it lie flat without tearing or folding (it’s actually impossible to make spheres lie perfectly flat this way), but those dots will also lose some of their clarity, getting bunched up or pulled apart. Considering the stuff where the dots would be on a globe is all of the Earth’s geography, this is a problem.
The most common map in the world gets around this problem by making the dots (ie: the land), at the top and bottom larger to account for the stretching, but this does distort distances (although, conveniently, it means that if you move in a straight line on the map, you also move in a straight line in real life, which is why it was used by so many people). Other maps get around this by stretching or squashing the dots. Each method has its upsides and downsides, but none can perfectly capture all of the information a globe provides at the same time.
Globes are very close to the true shape of the Earth, however the Earth is both slightly flatter than you would think, and also more lumpy. That said, the issues with a globe are much smaller than the issues with any map. You can generally rely on their accuracy.
An example of the dots (known to map makers as a **Tissot indicatrix**) with the most common (Mercator) type of map can be seen below. On a globe, all of the red dots would be the same size:
[https://upload.wikimedia.org/wikipedia/commons/8/87/Tissot_mercator.png](https://upload.wikimedia.org/wikipedia/commons/8/87/Tissot_mercator.png)
Everyone on here talking about mapping a sphere onto a flat surface, but forgetting about all the *human* biases. There’s literally no reason for the southern hemisphere to be the bottom of the map – the Earth floats in space and the universe doesn’t have a right side up
Imagine a strawberry. Now imagine you were in a situation where the exact distances between the seeds on its surface was of life or death importance to millions of people and you had to draw a picture of it to accurately depict those distances without using any words or numbers. And the map you drew was going to be given to someone who had never seen a strawberry before and didn’t know anything about them. How would you draw that picture?
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