Pole shift-iness

During an assembly this morning at school, the speaker, Harry Pickens, asked students what gave them hope and what worried them. One response in particular stunned me: The pole shift — the wandering of the magnetic pole toward Russia! I mean, what?

On my personal list of “things to worry about,” the drift of the magnetic pole from its present location in northern Canada toward Siberia is pretty low, somewhere near getting struck by heat lightning and being trampled to death by a wooly mammoth. But the remark did concern me as a symptom of poor critical thinking. The student in question (one of my former physics students — sigh!) had apparently picked up on the near-hysteria among the fringe-science crowd about the pole shift foretold by any number of psychics, channelers and “science experts.” [See an earlier blog about a radio caller’s fear of the earth flipping over around solstice time.]

Do a Google search on “pole shift” and there will be countless sites warning of an imminent reversal of the earth’s poles. Many seem a little hazy about the difference between magnetic pole drift and reversal, which is geologically evident, and the alteration of the earth’s actual axis of rotation. One site I visited completely muddled the concept of magnetic deviation, implying it was somehow a portent of catastrophe. Some sites are doomsday oriented, encouraging readers to prepare for sudden changes in climate, the relocation of the equator from its present location, tidal waves, floods, earthquakes, etc. Others predict the pole shift will bring on a new age, a new beginning for humankind. Books are advertised, Edgar Cayce’s predictions rehashed and reviewed, connections to Planet X, Nibiru, wandering asteroids made — the mind boggles.

It may make not one whit of change in all this pole-shift folderol, but here is my humble attempt of putting the pole shift controversy to rest. The “pole shift” won’t happen. I’d bet my life on it.

Let’s get a few concepts straight first.

Earth has two sets of poles: geographic and magnetic. They are apparently unrelated.

The geographic poles lie on the earth’s axis of rotation, at 90 degrees N and S. If you stood at either pole (dress warmly, it’s cold there!) at night, the stars would appear to wheel around you and an imaginary point directly over your head. An imaginary line drawn from the north geographic pole to that imaginary point would pass very close to the North Star, currently Polaris in Ursa Minor (the Little Dipper). I say currently because it’s been known since antiquity that the earth’s axis slowly wobbles in a circle. This wobble (more properly called precession) takes 26,000 years for one cycle, and results from the gravitational tugs of the moon and the sun on our spinning homeworld.

Despite what the fringe science and doomsday sites may say, there is no reliable evidence that the earth’s axis has ever deviated from this gradual precession. The earth’s mass is about 6 x 10^24 kg (much, much heavier than all the world’s population put together) and the planet is spinning fast enough that a point on the equator is moving about 1600 km/h (1,000 mph) relative to the fixed stars. Something that massive spinning that fast is a colossal gyroscope, and gyroscopes have a remarkable reluctance to suddenly change their axial orientation. So it will take somewhat more than an encounter with a passing asteroid or melting ice caps to flip the earth upside-down, or even knock its axis off kilter.

The earth magnetic poles live a separate existence from the geographic poles. Each is a region a few hundred kilometers in diameter from which the geomagnetic field emanates. One currently lies close to the northern territories of Canada, and as mentioned above, is slowly drifting away from that location toward, eventually, Siberia. The other lies just off the Antarctic coast roughly opposite its partner in the north, and is also slowly drifting. They have been moving randomly like this for millions of years.

Geologists say the earth’s magnetic field results from the churning of its liquid iron-cobalt core. Electrical currents in the liquid core generate the field, which reaches millions of miles into space, trapping charged particles in the van Allen radiation belts and directing others toward the magnetic poles where they ionize the atmosphere to make the Northern and Southern Lights — the aurorae.

There is geologic evidence that the magnetic poles of the earth migrate and have even flipped polarity. What effects magnetic reversal would have on the earth’s geologic activity and life are purely speculative. Some animals navigate using the geomagnetic field, so a pole reversal might have them flying the wrong way, perhaps. Sudden climate changes, increases in tectonic activity, etc., are not likely to happen.

Magnetic deviation, by the way, is a result of the difference in location between geographic and magnetic pole. A compass points to the magnetic pole. To locate “true north,” one must add or subtract a few degrees to the compass heading. This angle of deviation is well known to Boy Scouts, orienteering fans and ship captains, and is published in tables. Magnetic deviation is not a portent of doom, and is different from polar drift.

One possible catastrophe resulting from the motion of the magnetic pole westward could be tourism in Alaska. The locals there fear losing the nightly auroral show. See
this link.
Aside from that, we seem pretty safe.

Here’s a brief presentation of pole magnetic drift from NASA.
Finally, here’s an article calling mapmakers to task for inappropriate labeling of the magnetic poles, from the American Geophysical Union.

Aurora Borealis: The Magnificent Northern Lights 2006 Wall Calendar

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