When I was a young'un, as a Boy Scout, learning how to read a map and use a compass, we had to learn about magnetic declination. The compass did not point to true north, it pointed to magnetic north, which in central Louisiana was about 6 degrees east of magnetic north.
As a young Army officer several years later, this was important Land navigation was all about map and compass. The first thing we checked on the bottom of the map was the declination diagram, which showed the difference between the actual north pole, and some spot in Canada where your compass was pointing.
For no particular reason, I decided to check the local declination and found that it is zero degrees. Magnetic north is moving, and will sometime in the future, be somewhere in Putin's Siberia.
Of course, no one uses map and compass today. Today, it's all about GPS navigation, but I find it strangely interesting that the magnetic pole is moving, and has been for some time.
One of the things I learned as a young Armor officer is that a compass will not work in a tank. Too much steel around you. All land nav in a tank was terrain association. I was thrilled when the Army put GPS sensors in the M60A3 series.
5 comments:
Magnetic North is always moving, and in the late 1990s and early 2000s the speed was increasing. (I was learning navigation when I was learning to sail.)
The declination and variance also differs by location.
There is some thought that the poles will reverse, north for south in the near future. (Near - on a geological scale.)
I used declination last year when my neighbor tried to claim some of my property was his. I took a compass and a 300 foot tape, looked up our local declination, then proceeded to march every pin on our deed. And whadya know, the property corners where exactly where they were supposed to be! But only if you use the declination to coorrect your compass!
Even without declination correction, a compass and map are useful as a reality check (my old handheld GPS did not give correct compass direction unless it was moving).
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The Navy still uses 'magnetic' compasses on ships and in airplanes, and there is actually a procedure called boxing the compass to 'correct' declination cards.
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