Why Do the Magnetic Poles Change So Regularly?

[Boris_Badenov]

The Earths magnetic poles flip about every 250,000 years. Why?<br />Do the magnetic poles change because we rotate the galactic center? The North Pole of Earth is facing away from our direction of rotation in the Galaxy (I think), does that orientation change, & the magnetic poles flip? What are the current theories about why the poles flip? When is the next flip due? What effect will that have on Earths life?<br /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[enigma10]

http://www.madsci.org/posts/archives/nov98/912372013.Es.r.html <div class="Discussion_UserSignature"> <em>"<font color="#333399">An organism at war with itself is a doomed organism." - Carl Sagan</font></em> </div>

 

[search]

Very nice site enigma10<br /><br />Take a look at this animations:<br />http://www.psc.edu/science/glatzmaier.html<br />http://www.psc.edu/research/graphics/gallery/geodynamo.html<br /><br />Different levels of explanation:<br />http://www.windows.ucar.edu/tour/link=/glossary/mag_field_reversals.html&edu=high<br />

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>The Earths magnetic poles flip about every 250,000 years. Why?<br />Do the magnetic poles change because we rotate the galactic center? The North Pole of Earth is facing away from our direction of rotation in the Galaxy (I think), does that orientation change, & the magnetic poles flip? What are the current theories about why the poles flip? When is the next flip due? What effect will that have on Earths life? <p><hr /></p></p></blockquote><br /><br />Short answer: nobody really knows why they flip fairly regularly.<br /><br />Long answer: but they do have a lot of good ideas; they're just not refined enough to actually pinpoint the date in advance. It's not because of the Sun's slow dance around the galactic center; we're much too far from the galactic center for it to have any real effect on us, and although the interstellar medium is filled with charged particles, it is too diffuse to have that profound an effect. The big theories right now relate to the behavior of magnetic fields when the substance generating those fields is a) rotating and b) liquid. Glass spheres filled with ferromagnetic liquids behave in a startlingly similar way to the way the Earth's core is thought to behave, producing an overall magnetic field that has eddies and which reverses its orientation from time to time -- just as the Earth's magnetic field does.<br /><br />The answer to why it happens may have as much to do with fluid dynamics as it does with magnetism. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[3488]

Are the magnetic pole reversals due to the Outer Core of our planet having differential rotation, the poles slightly slower then the equator, causing the magnetic generation to weaken then flip over (much like the Sun, but molten Iron instead of Gas / Plasma)?<br /><br />Andrew Brown. <div class="Discussion_UserSignature"> <p><font color="#000080">"I suddenly noticed an anomaly to the left of Io, just off the rim of that world. It was extremely large with respect to the overall size of Io and crescent shaped. It seemed unbelievable that something that big had not been visible before".</font> <em><strong><font color="#000000">Linda Morabito </font></strong><font color="#800000">on discovering that the Jupiter moon Io was volcanically active. Friday 9th March 1979.</font></em></p><p><font size="1" color="#000080">http://www.launchphotography.com/</font><br /><br /><font size="1" color="#000080">http://anthmartian.googlepages.com/thisislandearth</font></p><p><font size="1" color="#000080">http://web.me.com/meridianijournal</font></p> </div>

 

[harmonicaman]

...or the molten core rotates at different speeds at the poles and equator! Likely the change occurs for the very same reason the Sun changes every 11 years; except in our case, the rotation is much, much slower so the change happens in slow motion for us.

 

[search]

According to this yes<br />http://gsc.nrcan.gc.ca/geomag/nmp/reversals_e.ph

 

[Boris_Badenov]

The link does not work. <br /><br />http://gsc.nrcan.gc.ca/geomag/nmp/reversals_e.ph <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[vandivx]

its http://gsc.nrcan.gc.ca/geomag/nmp/reversals_e.php<br /><br />need to add 'p' to it <br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[search]

Thanks V.<br />Thats it <br />

 

[CalliArcale]

<blockquote><font class="small">In reply to:</font><hr /><p>Pole reversals are not regular.<p><hr /></p></p></blockquote><br /><br />They're regular in much the same sense as volcanoes and hurricanes. That is, you can statistically predict that there's a good chance of one happening in x number of years, but whether it actually does or not is another question, because you're right -- it's a very complex system. (That's the main reason it's so hard to pin down the specifics of what causes pole reversals.) However, there is enough of a pattern to conclude that they are normal events, and merely something that occurs when you've got a geologically active planet like this one.<br /><br />One of the original poster's questions that I forgot to answer pertained to the affect on life. Many pole reversals have happened during relatively recent history (geologically speaking), including at least one while there were humans on Earth. They seem to occur more frequently than major evolutionary shifts occur, so I think it's safe to conclude that life will go on pretty much as it has for millions of years. Animals which use magnetic navigation may have a hard time, but they've all got other ways of navigating as well, so I don't think it'll be a serious problem for them. More of an annoyance than anything else, as their magnetic landmarks will shift. Based on the paleontological record, they seem to figure it out, though.<br /><br />Technologically speaking, it will cause some issues with navigational instruments, although with more and more devices switching to GPS, it will probably not be all that big of a deal. (GPS devices will be unaffected. Only magnetic compasses will be affected.) The biggest serious hazard will come from increased numbers of charged particles reaching the Earth's surface, causing electromagnetic effects in sensitive equipment. This could result in things as benign as personal computers acting flakier than ever, to things as serious as faults in medical devic <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>

 

[MeteorWayne]

Calli:"Animals which use magnetic navigation may have a hard time, but they've all got other ways of navigating as well, so I don't think it'll be a serious problem for them. More of an annoyance than anything else, as their magnetic landmarks will shift. Based on the paleontological record, they seem to figure it out, though. "<br /><br />I read an article within the last few weeks that provided evidence that migrating birds use a magnetic reference at night, but recalibrate it at sunrise or sunset based on sky polarization and the location of the sun. So they have ways of adapting.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[Boris_Badenov]

From the Encarta Encyclopedia;<br /> <br />Regular<br />reg·u·lar [ réggy&#601;l&#601;r ] <br /><br /><br />adjective <br /> <br />Definition: <br /> <br />1. having equal times or spaces between: occurring in a fixed, unvarying, or predictable pattern, with equal amounts of time or space between each one<br />the regular tick-tock of the clock<br /><br /> <br />2. happening frequently: occurring or doing something frequently enough over a period of time to establish a pattern, though not necessarily a strict one<br />Floods are becoming a regular occurrence around here.<br /><br /> There was more, but I thought this was enough.<br /> <br /> <div class="Discussion_UserSignature"> <font color="#993300"><span class="body"><font size="2" color="#3366ff"><div align="center">. </div><div align="center">Never roll in the mud with a pig. You'll both get dirty & the pig likes it.</div></font></span></font> </div>

 

[MeteorWayne]

That doesn't really help resolve the issue.<br />Between the definitions, it's in the grey area between regular and irregular.<br />Sort of like planet, or not a planet. <img src="/images/icons/smile.gif" /> <img src="/images/icons/laugh.gif" /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[harmonicaman]

There's also some anecdotal evidence (put forth mostly by various fringe science groups) that when the pole reversal occurs, the Earth will be left for a time with no protective magnetic field to ward off Solar radiation and this will result in a huge die-off and trigger an ice age. <br /><br />Some believe that ice ages are the direct result of pole reversals, but most mainstream scientists believe it's a non-event which will have a minimal impact on the Earth -- we'll see who's right! <img src="/images/icons/rolleyes.gif" /> <br />

 

[vandivx]

<"GPS devices will be unaffected. Only magnetic compasses will be affected."><br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>Although fast by geological standards, reversals are by no means quick on the human time scale. They take roughly 5,000 years, with estimates ranging from 1,000 years and 8,000 years.<p><hr /></p></p></blockquote><br />I guess I won't be out of pocket money having to buy a new compass anytime soon LOL<br /><br />I should think that technology changes over 1000 yrs plus render such concerns mute <img src="/images/icons/smile.gif" /><br /><br />maybe every fifth generation might have to recalibrate their compasses when the time for reversal comes, big deal, not like anybody will get lost in woods on account of changed magnetic bearings methinks even if he carries on him his grand grand grand fathers compass <br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

 

[CalliArcale]

You might need to recalibrate your compass periodically if you live in northeastern Canada, but otherwise, yeah. <img src="/images/icons/wink.gif" /> No real impact in our lifetimes, almost certainly. <div class="Discussion_UserSignature"> <p> </p><p><font color="#666699"><em>"People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff."</em>  -- The Tenth Doctor, "Blink"</font></p> </div>