Polar Orientation

This is one for the "duh" file-- those things that are more or less obvious in retrospect, but unknown because you never have any reason to stop and think about them.

To start with, let's have a quick refresher on magnets.  All magnets have two poles, conventionally called "north" and "south."  Opposite poles attract, and like poles repel, so the north pole of one magnet will push away the north pole of another, or be instead pulled toward its south pole.

Now we shift gears, and refresh our geology a bit.  The earth has a magnetic field, generated [oversimplification] by its spinning molten iron core.  The North Magnetic Pole is in the north, although NOT at the geographic north pole.  It's actually in Canada, up north of Baffin Bay, and currently wandering in a vaguely Russian direction.  See above re: molten core; fluctuations and eddies and whatnot cause movement etc etc and that's beside the point.

Now put them together.  Look at a compass.  The needle is a magnet, with a north and south pole.  The north end points north-- that's the whole point of the compass.  But wait-- the north end of a magnet is attracted to south poles of other magnets.  Which means, logically, that the magnetic pole in the north is actually a south pole.  The North Magnetic Pole is a south magnetic pole.

I thought that was rather cool, actually.