Saturday, February 26, 2011

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

[Note: This is one of the better articles I've seen lately on the Magnetic Field of the earth, and best explains the science behind the ongoing shift.--Lori]

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.

“At Washington D.C., the compass points 10 degrees to the west of true north," Jeffrey Love, USGS advisor for geomagnetic research, told "And this is increasing at Washington at a rate of about 1/10 of a degree per year.”

But don't touch that calibration dial just yet: The accuracy of compasses fluctuates with the field, he said, meaning compasses are more or less accurate depending on where you use them.

“It's different at different places on the earth,” Love said. Read More