eli5 How do we decide which one is North Pole and which is south pole? The space is almost infinite on all directions. So what we see on map might be wrong right? I mean it could also be upside down too.
In: Earth Science
As the others have said, the rotation of the Earth (or any sphere) means there are two spots on its surface that don’t “move”, and those are the poles. In addition, an arbitrary convention to use the [right hand rule](https://en.wikipedia.org/wiki/File:Right-hand_grip_rule.svg) to mark North vs. South, to match the convention we have for the magnetic poles for the Earth’s magnetic field, means the poles are where they are right now.
The best way I can think of to explain it is this: Cartography, to make maps consistent, had to create a common system of orientation. The names given to the directions are based in certain old words, for example East rooted in an old Germanic word meaning towards the sun. As far as why we decided to orient modern maps the way we do, it likely comes from Europeans seeing themselves as being the top, and the rest of the world the bottom, as the map is no less accurate if you flip it upside down. It could also be possible that the natural magnetic poles played a part when compasses were invented, and someone decided a compass points up when doing map orientation. I don’t know for sure, but I’ve seen maps before that don’t follow modern orientation from ancient times, and they seemed to care more about the rising and setting of the sun.
It’s arbitrary. The axis of the earth creates two directions which persist, the spinning creates two other directions. The names for those are north (incidentally, the word north comes from the proto indo european word “net”, meaning left or below, because that was the direction which is left of you when you face the rising sun), south for the other direction, east for turnwise/the direction the sun comes up from and west for counter-turnwise.
The habit of having maps top north is also arbitrary, but understandable since the white european culture is located in the northern hemisphere.
Fun fact: before geographical maps took over, there were also hermeneutic maps dealing with a world view instead of the accurate depiction of land masses and water. Examples are the [Ebstorf world map](https://warnke.web.leuphana.de/hyperimage/EbsKart/#O9999/) (interactive, but german) and the Psalter map of London [see here](https://en.m.wikipedia.org/wiki/Psalter_world_map). Note that those have the EAST at the top. They’re literally oriented, since the orient is where the sun comes up, remember? Coincidentally, the orient was also the center of belief in those times leading to eastfacing maps.
The earth rotates around its axis, and its axis goes through both poles. It happens to wobble in its orbit, so the location of the North Pole actually changes. On top of that, the earth has tectonic plates that float around on a bed of mantle and magma, adding even more instability.
Basically the north pole is constantly changing, and will be in a slightly different spot every year.
Not to be confused with the MAGNETIC North Pole, which actually exists near the southern geographical pole. Kinda confusing I know. But your North compass points North, because it’s attracted to the South magnetic Pole, which is at the geographic North Pole.
There is an angle calculated called the “declination” which is the angle formed by the magnetic North Pole, and the geographic North Pole.
This angle is constantly changing because the magnetic North Pole, as well as the geographic North Pole are constantly changing.
Kinda cool!
And there is no upside down on a map. Down is towards the centre of the earth only.
The Earth spins on an axis. This naturally creates an objective (if invisible) “pole”. This has nothing to do with space and only with Earth and the fact that it spins on an axis.
Also, there is no being “right” or “wrong.” This is a decision we, as people, get to make. And we, as a group, have decided that one end of the pole is North and one is South. There have been groups of people throughout history that decided the opposite of the current convention (notably Ancient Egypt) but in the end the current convention won out and became the most popular.
It’s just how people decided to map the world. The North Pole is at the “top” of the world if you travel north, the South Pole is at the “bottom” of the world if you travel south. Early people had to agree to how they would map out the earth and orient themselves to maps so they could coordinate travel and trade and all that good stuff.
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