On maps, why is North always up? Apparently, it's been this way only since the middle ages when Ptolomey's maps were rediscovered. Before that, it was a free-for-all.
Even more confusing is the fact that Magnetic North keeps moving , flipping around like a fish in a bucket. It's on it's way from Canada to Siberia at 41km/year as we speak. Actually, it may jiggle up to 85km in a single day and apparently is rarely found where it is supposed to be!
Compasses - despite popular belief- do not point North, or even to Magnetic North! Compasses point along LOCAL magnetic field lines- these are wobbly, and depend on moving flows of iron and nickel deep within the earth. The difference between where your compass is pointing and where true (geographic) north is, is known as Magnetic Declination. Off the coast of Madagascar, this can be up to 40 degrees!
Even True North- the geographic North Pole is moving ("Polar Motion") - albeit very slowly, and very slightly. It takes a cycle of about 400 years, but the point the Earth is twisting around moves by up to 20m. (see chart below). I guess we are tumbling rather than twisting our way around the sun. Fascinatingly, some of this is due to melting of the Greenland ice sheets and the subsequent rebound of the unburdened earth! Global warming is literally throwing the Earth "off kilter".
Finally, thanks to "precession" - like the wobbling of a spinning top- True North points to varying regions of space. Currently (in the northern hemisphere) it points to Polaris (aptly named!).