Why do we say North is up? People commonly refer to North as being up simply because North is at the top of most maps. If you think about how people talk about directions, many people use the phrases:

"up North"
"down South"
"out West"
"back East"

All of this originates from a view of the world with Europe or the east coast of North America at the center. This all begins to make sense when you know that the first people who tried making paper maps of the whole globe were Europeans trying to circumnavigate the Earth. Their problem was that the Earth is like a sphere, and they wanted to make their maps on a flat piece of paper.

How would you solve this problem?
The way that the mapmakers (or cartographers) solved this problem was to invent "projections". They looked at the globe, as if from outer space looking down on Europe at the center. There are many different projections.

What do you think would have happened if the first mapmakers were from Australia or Antarctica? (hint: try looking at a globe, but holding it so Australia is at the center)

In fact, you made a very good observation. The directions we choose are completely arbitrary.

North is up only when you are looking at a map . If the map is on a horizontal surce (like a table) then by convention we portray the "up direction" NORTH.

Now if you really want to go outside and face the north direction, this is what you can do:go out on a cloudless night and find the pointer stars of the BIG DIPPER.

These two pointer stars in the cup point to a star called Polaris, which is in the constellation called ursa minor (or little dipper). Now drop a line through polaris to the horizon...where that line intersects the horizon is the NORTH direction. If you have a earth map point the UP in the same direction...then the map will be properly aligned.

You also can buy a compass and the red arrow of the compass points north.

You've asked an excellent question. In general, map makers have agreed to put north at the top of maps. That makes it easier to compare one map to another.

One reason for doing this is that people tend to recognize shapes most easily when they are in the same orientation. To see if this is true for you, try turning a world map upside down (put south at the top) and then identify the continents. This test is quite hard for most people.

Some people, however, are good at "mental rotation"--they can imagine a shape like Africa in their heads and then turn it to a new orientation. But all of us occassionally need to turn maps to recognize where we are, for instance, when driving a car. Then you may see someone turn the map so that the view out the window matches the printed streets.

For world maps, because we often put them on a wall, north really is up, and south is down, even though on earth those directions are both horizontal.

Sometimes people print maps in other orientations so they make more sense. And sometimes they do it as a kind of joke, like in Australia, where maps are sometimes printed with south at the top, since they are living "down under."

In ancient times, maps were usually drawn with east at the top, since that way Jerusalem was toward the top of the map.

Later, maps were oriented with north at the top for sailing ships, since that made it easier to do navigational calculations and use a magnetic compass.

Today there are many electronic map systems that allow maps to be displayed with north in any direction. Having north at the top, though, is still often the easiest way to recognize where you are.

I think north is "up" because when we put a map on a wall north on the map is in fact "up" relative to the bottom. Even when we lay a map on the table we still think of the top and the bottom of the map. North is always at the top of the map, so we tend to say north is "up."

Now, why have we always put north toward the tops of our maps? That is a different question, and I haven't the foggiest clue. All I know is that the map makers in the Medieval period centuries did it that way, and we have been doing it the same ever since! Let me know if you get an answer from someone who knows.