True North, Magnetic North
Many centuries ago, mariners oriented themselves by the sun’s place or rising and setting, or by the direction of the prevailing winds. This was less than precise, especially on windless or cloudy days. The magnetic compass, perfected slowly over years of experimentation, trial and scientific endeavor, became the sailor’s most common and most reliable direction-indicating aid. In principle, the magnetic compass remains as simple as it was when it was invented in medieval times. It is a magnet, balanced so it can pivot freely in a horizontal plane. The magnet — as any magnet will, given the opportunity — aligns itself with the earth’s magnetic field. A pointer attached to the magnet will point the way toward the north magnetic pole. The north magnetic pole is near, but not the same as, the earth’s true north pole, or axis of spin. The magnetic pole wanders somewhat over many years, and is located in far northern Canada.
Grades: 4-8
Disciplines: Geography, Math, Science
