Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Will the Earth's magnetic poles flip?

  1. Mar 25, 2005 #1
    I just watched a documentary on the history of the Earth's magnetic field that was very interesting. It said that the Earth historically has averaged a pole flip roughly every 200,000. However, Earth has not flipped its poles in over 700,000 as evidenced by ferromagnetic iron samples taken from varying altitudes of volcanoes all over the world. Essentially the process is like this, when magma cools to a certain temperature, the iron in it, which is ferromagnetic (aka. the iron is divided into finely divided sections which each carry a magnetic dipole moment in random directions), is acted upon by the Earth's magnetic field at the moment of cooling and therefore the iron's finely divided sections all take on the same North / South 'compass' direction as the Earth currently had at the time.

    So you see, by radiometric dating and establishment of the age of the magma from where the iron came from, you can simply check the direction of their dipole moments and whence after taking many samples, track the points in time when the poles flipped!

    It should be noted that the radiometric dating methods used have large error factors when predicting the date of the magma's cooling, yet still the rough interval between pole flips i quoted as 200,000 years gives you a good sense of a reasonable time scale in which pole flips occur on average.

    Clearly, if we are in the midst of the beginnings of a current pole flip (we are ~500,000 years overdue anyhow), its power to reverse the seas and melt the icecaps will most assuredly outshadow any of the human environmental vices that impact our Earth's current global warming.

    In short, our ills upon nature are still juvenile compared to nature's ill upon itself.

    What do you think?
  2. jcsd
  3. Mar 25, 2005 #2


    User Avatar

    Staff: Mentor

    Some scientists think we are in the midst of a pole flip right now: the magnetic field is reducing and over the next few centuries (I think thats the timeframe), it'll probably flip.

    But I don't know where you would get the idea that it would even be noticeable to anyone not carrying a compass.
  4. Mar 26, 2005 #3


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    What has this topic got to do with the book Visions ?
  5. Mar 26, 2005 #4

    Ivan Seeking

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I haven't read up on this, but from what I've heard, one concern is that of shielding. How did life survive the last flip with nothing to protect the planet from the sun's radiation [ie. flux of charged particles, esp when solar storms are active]? IIRC, Janus was talking about this at dinner. There is an idea, or a model that shows that the influx of charged particles would produce its own magnetic field and provide protection during the pole reversal - through the zero point.
    Last edited: Mar 27, 2005
  6. Mar 31, 2005 #5
    I was thinking of the same thing. Only I only took it to the extent that we would get some amazing aurora :!!) - not considering any concequences (and with no mag field, no aurora, right?)
    Would they use the magnetic polarity or the geographical polarity to decide whether it is Aurora Borealis or Aurora Australis? :rolleyes:

    Another lame unimportant concequence is that lazy private pilot licence students like my self need to get that deviation card updated and put into use! When flying after the terrain the deviations here in Norway are too small to even bother about - although they are significan enough for IFR flying. :redface:
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook