 The compass, perhaps the oldest navigational tool of man, does not point to the geographic north pole with its needle. Instead, it indicates the magnetic north pole — which, though close to the geographic north pole, is not at the “top” of the earth's axis. It is actually in the Artic Ocean north of Canada, and moves as the magnetic fields of the earth change.
The molten iron core of the spinning earth makes it a giant magnet. However, that magnetic field is actually moving. Jeffrey Love, a research scientist with the U.S. Geological Service’s Geomagnetism Program, notes: "So that means if you wait five years, the compass will be off by one degree." During some periods the drift of the magnetic north pole has been relatively slight. When it was first identified in 1831, it remained fairly stable for decades. Then, beginning in 1904, scientists began to observe a northeastern shift of about nine miles a year. Since 1989, the drift of the magnetic north pole has accelerated to about 35 miles a year in the direction of Siberia. end quote. As a result of this ever increasing movement every year airports around the world are scrambling to keep their magnetic north coordinates up to date. Only with GPS receivers can you be sure where you are these days unless you are just flying, walking, driving or sailing by landmarks. OR I suppose you could find out where you are if you have starry nights with a sextant. | |
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