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Surprisingly Rapid Changes In Earth’s Core Discovered

  1. Aug 1, 2008 #1

    One wonders what other effects those rapid changes may have on the Earth mantle, considering heat and mass distribution and ultimately the dynamics of the earth in total. Could any of the 'not understood' phenomena from the geologic past be tied to causes in the Earth core?
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  3. Aug 1, 2008 #2
    I wish it went into more detail about how fast it changes, if it changes on a regular pattern or if its a random change. It would be interesting to speculate about times in the past when geo-magnetic reversals occurred, and the causes that led up to them.
    I guess we wait for a the full report.
  4. Aug 1, 2008 #3
    It's mans fault. Geothermal energy has been changing the earths core temperature for years. So has radio. Let me show you my hockey stick diagram.

    On a more serious note, my sincerest hope is that this research is promoted from position of new data being found rather than a position of new changes being found. I'd much rather have this be something studied for years (possibly hundreds) than to have science immediate turn around and say that these changes are new and therefore must be man made/natural precursors to disaster/signs of the end of the world.
  5. Aug 1, 2008 #4


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    Will they have to start diverting aircraft from the low magnetic regions?
  6. Aug 1, 2008 #5


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    Re: Surprisingly Rapid Changes In Earth’s Core Discovered

    Well satelites at least. The low field region off the coast of Brazil is known as the South Atlantic Anomoly, because of the low field the radiation belts reach further down and effect satelites flying through them. One of the worst affected is Hubble, some of it's instruments have to be reset every time it goes through the SAA, costing a serious amount of observing time.

    It might have a radiation dose effect if anyone was still flying Concord to Rio, or had any SR71s cruising around Cuba.
  7. Aug 3, 2008 #6
    This is interesting because the geomagnetic field as measured at the surface is subject to diurnal variations and other such phenaomena such as magnetic storms which would tend to cover up rapid changes in the geodynamo component of earth's magnetyic field. I presume measuring from satellites gives a higher signal:noise data set of this geodynamo component, and so we should use these data to see a truer surface expression of the earth's engine at work. Of course the signal we get is still altered by convolution with complex geophysical heterogeneities that we do not fully understand. It is interesting though that similar research (which has looked at historical magnetic data) has revealed the presence of slow westward drifting non-dipolar anomalies that seem to correspond to areas of ultra-low seismic velocity at the core mantle boundary. Some people have proposed that these anomalies are related to tectonic slabs which have subducted all the way to the base of the mantle!
  8. Sep 2, 2008 #7


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    It is not so much that the instruments need to be "reset," as it is that the ionization track produced when an energetic charged particle passes through matter will generate a spurious signal if the matter in question happens to be one of the pixels in the Hubble's CCD cameras. (I.e., CCDs also detect ionizing radiation, not just photons.)

    If one examines the "raw" CCD frames from a spacecraft's CCD camera, there are always a small number of pixels that are "whited out" because a cosmic ray or other energetic charged particle passed through that pixel during the exposure. The Hubble orbits at a high enough altitude that when it passes through the portion of the Van Allen Belt that dips down into the region above the SAA, the increased radiation degrades the CCD's signal-to-noise ratio to the point that many of the CCD frames that would be taken while passing through the SAA would be useless.
  9. Sep 5, 2008 #8


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    I believe these signal polar shift being underway. If that is true, could anyone please tell me if the shift is actually a dead-end or is there something being done to ensure that the flora and fauna is impacted less?
    I read up a bit and found that the the so-called end of earth is predicted to be in 2012. Is this anything that one really needs to be worried/terrified about? And is anything being done about this as a concern for the earth in general???
  10. Sep 5, 2008 #9
    Welcome to the forum MP1 and relax. Nothing of that kind is going to ruin your life. The 2012 end of the Mayan calendar and Earth thinghy is crank.

    On the other hand, that doesn't mean that we have a clear idea about what has been going on and what's happening right now inside that Earth.
  11. Sep 6, 2008 #10


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    As the previous poster has noted, the 2012 End Of The Mayan "Long Count" Calendar nonsense is exactly that: Nonsense. It's the exact equivalent of those who were irrational enough to have believe that The World Will End with the Year 2000 (or 1900, 0r 1800, or 1700, or 1000, &c., &c.), simple because the digits rolled over. The Universe does not give a frozen fig about when the Mayan Calendar, Gregorian Calendar, Hindu Calendar, or any other arbitrary human method of keeping dates happens to complete some cycle.

    Regarding geomagnetic pole reversals, they are expected to be mostly harmless. First of all, even if the Earth's magnetic field were to disappear entirely, the Earth's atmosphere is more than thick enough to screen out the overwhelming majority of cosmic and solar radiation. [The earth's atmosphere has about the same stopping-power as nearly a meter of lead shielding, because a pressure of 1 atmosphere implies that there is a column-mass of about 1033 grams of air above every square centimeter of the Earth's surface, while the density of lead is 11.34 gm/cm^3, and to a first approximation, radiation shielding power depends primarily on the integrated amount of mass between the target and the radiation source. So the shielding power of the Earth's atmosphere is roughly equivalent to about 91 cm of lead.]

    Second, both the paleomagnetic data and the results of computational simulations indicate that the Earth's magnetic field does not vanish completely during a geomagnetic reversal. The data indicate that the dipole component basically just "tips over" from "North" to "South" orientation over a period on the order of ~1000--5000 years, and that its magnitude never falls below roughly 10% of its "nominal" value during the reversal process --- and a 10% nominal geomagnetic dipole moment is still strong enough to deflect the overwhelming majority of incoming cosmic radiation and solar wind plasma.

    Third, numerical simulations indicate that during a geomagnetic reversal, the magnetic quadrupole moment begins to grow as the dipole component weakens, reaching a maximum at about the same epoch that the dipole component reaches its minimum as it "tips over." So at no point during the reversal does the geomagnetic field completely vanish; it just becomes temporarily more complicated.

    Finally, please note that the Earth's geomagnetic field has reversed hundreds of times during its history --- yet these events show no statistically significant correlation with "mass extinctions."

    So at no time during a geomagnetic reversal does the Earth's magnetic field ever drop to "zero," but rather, it remains strong enough to shield the Earth at all times --- and even if it did drop to zero, the Earth's atmosphere would still provide sufficient shielding to protect its biosphere.

    Migratory species that use the Earth's magnetic fields for navigation may get a bit confused while the earth temporarily has an "East" pole and a "West" magnetic pole (plus perhaps a few "extra" poles) instead of just a "North" and "South" magnetic pole --- but since most such species use multiple external clues to navigate by, it's unlikely that any of them will go extinct during the evolutionarily short timescale of a geomagnetic reversal. (For example, many species of birds use magnetic fields to navigate, yet birds have not gone extinct despite hundreds of geomagnetic reversals since they evolved --- and experiment shows that they can still navigate even if one glues magnets to their heads.)
  12. Sep 6, 2008 #11


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    Actually, we do have enough surface and satellite measurements of the Earth's magnetic field to make a pretty good inference of what's happening at the core/mantle boundary, assuming that mantle electrical conductivity can be neglected.

    The data suggest that nearly all geomagnetic variations can be accounted for by assuming a small number of "reversed-field patches" where the magnetic-field component normal to the core/mantle boundary reverses sign. These reversed-field patches almost certainly correspond to anticyclonic fluid vortices in the convecting liquid outer core (PDF, 4.7 Mb), and are probably roughly analogous to the "Highs" in the Earth's atmosphere, or the Great Red Spot in Jupiter's atmosphere. In particular, the strongest reversed-field patch corresponds quite well to the South Atlantic Magnetic Anomaly. The reversed-field patch below Africa is currently growing rapidly and drifting westward, while the other three major patches have remained more or less stable.

    So a fairly reliable scenario is the following: The South-African reversed-field patch and perhaps one or two other reversed-field patches will continue to increase in strength and diameter, just like some reversed-field patches have been observed to do in geodynamo simulations. As the reversed-field patches strengthen, the net dipole component of the Earth's field will weaken and begin to "tip over," while the quadrupole component will strengthen. Eventually, the South-African patch and the other reversed-field patches will become strong enough and large enough that they will dominate the geomagnetic field, while the regions with the "old" orientation will continue to decay in strength and coverage. As the dipole component strengthens again in its new orientation, the quadrupole component will begin to decay, and the overall field will eventually settle down to a predominantly dipolar field of opposite orientation to its pre-reversal value, with just a few patches of the "old" orientation left --- one of which might eventually grow large enough to initiate a new epoch of field reversal.
    Last edited: Sep 6, 2008
  13. Sep 6, 2008 #12


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    I think WFPC was put into a safe mode where it continually flushed charge and so wasn't usable. I think there was also a concern about the behaviour of the computers.
    I think the radiation in the VA belts is a few 10Mev protons and I would have thought most would probably be stopped by the cryostat. Most cosmic ray events on ground CCDs are muons.
  14. Sep 6, 2008 #13


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    The van Allen energy distribution, like most natural distributions, has a long tail, of power-law-like form.

    Said muons are generated when a cosmic-ray primary hits an atom in the upper atmosphere. Since the atmosphere has roughly the same stopping-power as a meter of lead (i.e., on the order of 1e3 gm/cm^2, the mass per unit area of the column of air above the detector), relatively few cosmic-ray primaries make it through to the ground. (Muons get through because they don't couple to the strong force, so the scattering cross-section they see is much lower than that a cosmic-ray primary would see.)

    Above the atmosphere, the dominant cosmic-ray particles are high-energy protons, and a smattering of heavier nuclei, with a power-law-like energy distribution.
  15. Sep 6, 2008 #14
    The Ørsted satellite has been mapping the magnetic field for almost a decade. I'm surprised it would take that long. Wow. I'm glad to know scientists are actively engaged in solving these mysteries.
    Great! Now I have an idea for keeping my lab animals in place! I think I'll look at velcro, too.
  16. Sep 6, 2008 #15


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    The geomagnetic field has long been known to change measurably on a timescale of less than a decade. Since magnetic compasses are still useful for navigation and other purposes, and are therefore still vital to international commerce and to the various national militaries, it should come as no great surprise that the geomagnetic field still continues to be actively mapped by numerous interested parties --- since any map made more than about 10 years or so ago would now be significantly out of date today.

    Active and ongoing mapping of the geomagnetic field will probably continue, until no one needs magnetic compasses any more, and there are no other applications that still require that it be accurately known.
  17. Nov 12, 2008 #16
    About Van Allen's belts and computer behaviour:

    Guys at SSTL have built and operated dozens of satellites for decades at various low altitudes, and their observations are very clear.

    With modern semiconductors, no latchup was observed, never ever. They've dropped the power supply protection for years now.

    Lost bits do exist in dynamic Ram. They are always isolated, so simple error correcting codes are a perfect answer.

    The amount and sophistication of electronic equipment they've in orbit exceeds by far what old big companies have - because SSTL wasn't bound by agencies' preferred part lists.

    They consider that no Earth-satellite failure can be explained by radiation. But radiations are a comfortable excuse that points to no precise company.

    As for CCD sensors, it's a different situation, of course.
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