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calendar   Saturday - February 26, 2011

North By North South?

Oh Noes!! Compasses losing accuracy because Magnetic North Pole Is Drifting!!


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Sometimes I swear news stories are published just to scare people. Or to annoy those of us who can actually think. The magnetic north pole has ALWAYS been moving. As nifty as compasses seem when you’re a kid in Scouts, they all have this bit of inaccuracy built in. The truth is that they don’t actually point north. Or to the north pole. Or even to the magnetic north pole. The truth is that the compass needle aligns itself with the local magnetic field, a bit like a homing pigeon flying along a local ley line. And - no shir, Shitlock - those local field lines are not now, nor have they ever been, entirely parallel to the magnetic axis. This is what “magnetic declination” is all about. It’s also what you can avoid by having a GPS, or a device that has one built in. Like an iPad app. In the bad old days, we had to have paper maps available and know how to read them, and how to adjust them. The declination amount was shown at the top of the map. Yeah, an old map would have the wrong value, so you had to get new maps every decade or so. Big deal.


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No, this is NOT a newly discovered Jackson Pollock painting. It’s the earth’s magnetic field.



Ordinary Compasses Thrown Off by Changes in Earth’s Magnetic Field

The Earth’s magnetic field is changing at an increasing rate, throwing off airports and altering the aurora borealis—and its effect on ordinary compasses could mean the difference between homeward bound and hopelessly lost.

Earth’s northernmost magnetic point—or magnetic north—is distinct from its geographic North Pole, and scientists have long known that the magnetic poles are on the move.

But the magnetic poles have been moving faster lately, sliding towards Siberia at 34 miles per year at a speed that’s accelerated 36 percent over the last 10 years, according to the United States Geological Survey, or USGS.

Since compasses rely on magnetic north to point you in the right way up the trail, the average $2-dollar model could very well point you in the wrong direction. Depending on location and journey length, unaware hikers or boaters could find themselves hundreds of miles off course if they don’t calibrate for the shift, experts said.

Don’t forget that every once in a geologic while, the magnetic poles actually reverse themselves. It’s always been like that. And unless I missed the fine print statement that says how this is a magical and instantaneous shift, my understanding is that the magnetic pole goes from up to down by moving a little bit all the time.

And just for gits and shiggles, this Scary Science article above forgets to point out one salient fact: the magnetic north pole is moving northward over time:

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which means that compasses are actually getting more accurate for most of us, because the distance between the magnetic north pole and the rotational north pole is decreasing. The magnetic pole is not moving directly towards the rotational pole, but it’s many many hundreds of miles closer to it than it was a century ago. See here for more movement history. And don’t let science stories scare you. Half the time they’re pure crap.

For extra fun, know that the movement of the magnetic poles is most probably caused by movement within the molten core of the planet. “Core Flux”. Vast continental sized plumes of molten iron rising and falling and swirling around. That’s the accepted theory it seems. Yet somehow that more energetic core moving about, sometimes closer to the surface, sometimes further away, that vast and incomprehensibly large mass of molten iron sometimes hotter or cooler ... has no impact whatsoever on the temperature of the surface just 50 miles or so above it. No, it’s a microminimal change in the amount of a rare atmospheric gas that causes the surface temperature variations. Uh huh. Right.


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Posted by Drew458   United States  on 02/26/2011 at 07:21 PM   
Filed Under: • Amazing Science and DiscoveriesMedia-Bias •  
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