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    Re: no leap second coming in December
    From: Frank Reed CT
    Date: 2004 Jul 29, 13:53 EDT
    Casey M wrote:
    "I too find this rather interesting.  I read recently in the NY Times about some research describing that the magnetic field flips every now and then, between every 1,000 to 28,000 years and that it may be getting ready to flip in the next one or two thousand years."

    Although there has been some casual speculation that the Earth's magnetic field might be starting into a polarity flip, there's nothing to it but speculation. Most geophysicists dismiss the possibility (but agree that there is a low probability that it could occur soon). That time period you're refering to is the estimated time to COMPLETE a polarity reversal, by the way. The time between reversals ranges from a few thousand to hundreds of thousands of years, and it's not periodic in any simple way.

    One of the FAQs on the USGS geomagnetism site discusses this issue. The faq page is here:
    http://geomag.usgs.gov/faq.html

    And for some maps of the Earth's changing magnetic field, visit here:
    http://www.HistoricalAtlas.com/mag


    And:
    "If you do a web search on "magnetic flip" or similar, you'll find a lot of info.  It would be interesting to find a reference stating that the core flow changes could also be affecting the spin rate of the earth."

    Though it's possible in principle, there is no observed correlation between spin rate changes and magnetic field changes (at this time). They are essentially independent phenomena.

    Frank R
    [ ] Mystic, Connecticut
    [X] Chicago, Illinois
       
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