Become a fan of Slashdot on Facebook

 


Forgot your password?
Close
typodupeerror
×
Space Science

Solar Winds to Protect Earth During Magnetic Pole Reversal 80

Posted by CowboyNeal from the thank-the-heavens dept.
me98411 writes "A study published in April, hinted at possible anamolies/reversal in Earth's magnetic field. This study found that there is an anamoly in a large patch near South Africa where the Earth's magnetic field points in the opposite direction. Now, according to New Scientist, this planet might be safe during reversal of poles due to formation of replacement field created by interaction with solar winds. Phew! I was worried I will not be able to use my compass." Even better than compasses not being obsoleted, we won't be bombarded with dangerous levels of radiation, or so the scientists say.
This discussion has been archived. No new comments can be posted.

Solar Winds to Protect Earth During Magnetic Pole Reversal More

Solar Winds to Protect Earth During Magnetic Pole Reversal

Comments Filter:
  • The solar winds, which are charged particles being moved by solar radiation, will prevent us from being hit with charged particles and solar radiation?
    • Thats what I was thinking. Also how will compases work during the big switch thanks to the solar wind?
      This is a story from _April_.
      • Why use a compass? GPS is much more useful/geeky anyway.

        • Re:So Lemme Get This Straight.... (Score:5, Insightful)

          by PurpleFloyd ( 149812 ) <zeno20@@@attbi...com> on Saturday May 15, 2004 @04:36PM (#9163157) Homepage
          Because a map and decent compass don't cost more than about $25, require batteries, die when they get wet (you can easily get waterproof maps), or lose signal under heavy cover.

          I use GPS when I go hiking, but I would never trust it with my life; my compass, on the other hand, has been dropped, stepped on, crushed and generally ill-treated for about 15 years and has served me faithfully through all that time (although I have had to adjust the declination after a few of the really rough treatments). GPS is an incredibly useful tool, but it's never a good idea to trust your life to something whose batteries might go dead on you, especially when an excellent backup is easy to use, weighs only a few ounces, and can be had cheaply.

          • But when the magnetic field changes, your compass will be worth jack squat because you won't know whether it's pointing the right direction.

            GPS works regardless of the magnetic field, except in cases where a satilite goes out because of excess radiation, but thats why there's so many of them.

            • Re:So Lemme Get This Straight.... (Score:4, Insightful)

              by sethanon ( 26295 ) on Sunday May 16, 2004 @09:52PM (#9170391)
              You're using a once in a million years event (albeit one that may last for a thousand years) to claim that compasses aren't reliable?

              I suspect that if I go hiking tomorrow there is more chance of my GPS unit screwing up than the earth's magnetic field suddenly vanishing.

              The real point of the post you are replying to is: if you are going to stake your life on a piece of equipment, make sure you have a backup. Preferably something that has different failure modes.
            • Actually, a pole -reversal- would hardly obsolete compasses. Now what upper atmosphere changes would do to the delicate sensibilities of the many intertwined GPS sats is... beyond the scope of this post.
              • I'm a freelance writer writing a story for a major daily newspaper about what happens with your data when you die (a topic you posted to earlier this month). I'd like to talk with you and your counsin about this issue. Please e-mail me at jselingo at yahoo dot com and I could give you more information about the story and set up an interview. Thanks. Jeff Selingo
          • father(to son): boy, i have been using this compass for years! the red dot points to north, which is the geological south......
            err...wait, this points to south..geological north...
            err...wait...this is north ...this is south...geological north...
            son...good luck with this compass
            we had it easy before!

        • GPS???? *WHAT* GPS? (Score:4, Insightful)

          by darkonc ( 47285 ) <stephen_samuel&bcgreen,com> on Sunday May 16, 2004 @05:34PM (#9169361) Homepage Journal
          Note that the protective covering is going to be at the level of the ionosphere... This means that all of the satelites that were built with a presumption that they had the protection of the magnetosphere are gonna get royally fried when that protection is gone.

          Granted -- the current flock of satellites should be long gone by the time that happens, but this *will* raise the cost of LEO satelites over time.

      • Who gives a rats about a compass, there will be no magnetic field for them to work.

        We can always use the sun or other stars (Southern Cross in the southern hemisphere) to find where north is.
        • There will be a magnetic field of some sort, it just will have flipped. Magnetic north moves continually, which is why Navigational Maps tell you how far the north your compass is pointing is off from the true north. In this case, if the poles flip, after it's done, we'll just paint over the N,E,S,W and put S,W,N,E the compass is pointing in the opposite direction? So what, I've solved he navigation problem. :-P
    • I'm assuming that, since the charged solar winds are deflected by Earth's gravity, they set up some sort of magnetic field. Of course IANAPY (I Am Not A Physicist Yet)
      • Umm... Why would a massive body like Earth "deflect" particles (which have mass) with gravity? I'm not a physicist either, but as far as I know gravity causes atraction, not deflection.

        • The definition of "deflection" (Score:4, Insightful)

          by some guy I know ( 229718 ) on Saturday May 15, 2004 @11:04PM (#9164971) Homepage
          gravity causes atraction, not deflection
          "Deflection" is not the same thing as "repulsion".
          You can deflect something toward you.
          See here [reference.com] for a complete definition of "deflection".
          Now, one definition of "deflect" is "to turn aside", but that's not the same as "to turn away".
          For example, in a CRT, the stream of electrons is deflected in order to write to the phosphor screen.
          On some CRTs, this deflection is done by using charged plates.
          The result is that the beam is deflected away from one plate, but toward the other.
          The second plate deflects the beam as much as the first (actually, more so), and the deflection is toward the plate (i.e., the plate attracts the beam).

          So, it is possible for a mass such as the Earth to deflect a stream of particles toward it.
      • I'm going to assume you mean deflected towards the Earth, although not necessarily hitting us.

        I don't think that gravity is a significant player, here. The solar wind hits Earth at around 150 km/second. That's quite a bit in excess of Earth's escape speed, 11 km/sec. As a rule, something travelling a lot faster than the local escape speed isn't affected by gravity much.

        As a side note, while I was never much good in the field, I can't recall anyone taking gravity into account much in magnetospheres work

    • Re:So Lemme Get This Straight.... (Score:5, Interesting)

      by Jerf ( 17166 ) on Saturday May 15, 2004 @03:01PM (#9162776) Journal
      No, the interaction with the solar wind and the atmosphere will prevent us from being hit with charged particles.

      Solar electromagnetic radiation comes through no matter what and is not affected by the magnetic field. In fact, that's something of a similar situation: The Ozone layer, as I understand it, is formed by the very radiation it absorbs. That's why a hole in the Ozone layer forms over the pole that gets no sunlight; Ozone breaks down relatively quickly and without the production mechanism, eventually it all breaks down. It reforms again once it is hit by sunlight again. CFCs were theorized to accelerate the destruction rate of the ozone, which caused a net reduction in the amount there was, starting near the poles since they get less sunlight and already had a lower production pace.

      In the reverse direction, note that shielding can sometimes cause a net increase in dangerous radiation, as high-energy cosmic rays that would just pass through a person impact the shielding and bombard the shielded thing (like a person) with a series of lower energy radiations, which may total a lower energy overall then the cosmic ray but have a much greater effect on the person.

      Second-order effects very often swamp the first-order effects. This is one of those basic facts of mathematical thinking that is vital to understanding any sort of science, and is one of the reasons having politicians, and people who think they understand science but don't understand this kind of mathematical thinking, scare me so much. Statements like "Higher taxes mean more income", "more shielding means less radiation", and "a lower magnetic field means more radiation getting to the surface" may all sound like common sense, but they aren't; the former two are certainly not universally true (only true under certain circumstances, which if you don't understand the limits you will almost certainly be led astray), this article suggests that the same is true of the third.

      It's only confusing if you insist on trying to understand everything solely in terms of their first-order effects; the universe is far, far from that simple.

      That said, I have no idea if this simulation is correct or not; I merely observe that there's no reason to dismiss it because it contradicts the results of a simplistic analysis based soley on direct effects.

      (Minor nit: The solar wind is simply charged particles streaming away from the sun; they are not necessarily being moved by "solar radiation", which is really too generic a term in this context to be useful.)

      • Re:So Lemme Get This Straight.... (Score:5, Interesting)

        by gumbi west ( 610122 ) on Saturday May 15, 2004 @08:19PM (#9164289) Journal
        ...note that shielding can sometimes cause a net increase in dangerous radiation, as high-energy cosmic rays that would just pass through a person impact the shielding and bombard the shielded thing (like a person) with a series of lower energy radiations, which may total a lower energy overall then the cosmic ray but have a much greater effect on the person.
        Nice try, but according the the United Nation's report on the sources and effects of radiation [unscear.org], the dose rate is higher for pilots who fly over regions of lower magnetic field strength (look at the section on ocupational exposure). Lower magnetic field strength occurs near the magnetic poles, and is where lower energy particles can penetrate the magnetic field (areas of lower geomagnetic cutoff).

        Also, according to a paper in materials science research titled, Cosmic-Ray Neutrons on the Ground and in the Atmosphere [mrs.org] And a number of other papers by the same author, the measurements show that the cosmic contribution to background dose rate increases as the strength of the magnetic field decreases.

        The error in logic with your argument is that the magnetic field deflects particles before they reach the atmosphere and interact. Once they reach the atmosphere, they interact with the atmosphere (not the magnetic field) to generate the "more dangerous radiation." as you call it. That said, I'm not entirely sure that this radiation is any more or less dangerous. While it is true that the quality factor is lower (what you multiply the energy deposion by to get the increased quantity that is proportional to increased probability of cancer), the energy deposition can be higher (this is true for photons, but not electrons, and I just don't know for protons and higher Z charged particles with kinetic energies in the GeV range).

        • So, which part of "sometimes" didn't you understand?

          Specifically, in outer space, outside of Earth's sheilding effects, lead sheilding is spacecraft is eschewed because it exposes the astronauts to more dangerous radiation then less. That's why, among other reasons, the Apollo landers were made of the thinnest foil possible.

          Magnetic sheilding isn't the only kind of shielding, and trying to disprove a "sometimes" with two specific examples is just plain a logical fallacy. That's the error in your logic, no
          • Let me clarify. Your conflating earth's magnetic shielding with shielding using matter. In the case of earth (the one example I was using), a smaller magnetic field than present will always be worse--and that's what we are talking about here, earth and its magnetic field.

            You are right that matter can increase the dose equivalent rate, and even the air kerma rate, for certain high energy particles.

            High energy particles (neutrons or protons with more than 100 MeV of kinetic energy, for example) will interact

            • Let me clarify. Your conflating earth's magnetic shielding with shielding using matter. In the case of earth (the one example I was using), a smaller magnetic field than present will always be worse--and that's what we are talking about here, earth and its magnetic field.

              He is using high-density shielding as an analogy to illustrate why a simplistic evaluation does not always give the correct result. Nowhere did he say that it was _directly_ analogous to the magnetic field question, and from what I can se
              • Your right that I attributed to him an argument that he explicitly didn't support. That said, attacking him was not my primary interest.

                I was more interested in pointing our relevant research in the area of the article. And while his original assertion may be correct (concicely stated by you as 'it couldn't be dismissed out of hand without analysis') I was trying to provide reference to informative analysis that could be used to dismiss it.

                I'll admit that I got a bit over the top with the 'nice try' opener.

        • Re:So Lemme Get This Straight.... (Score:4, Informative)

          by king-manic ( 409855 ) on Monday May 17, 2004 @01:36AM (#9171201)
          Radition is dangerous because it severes DNA strands or other protien strands. Normal protien strands that are damaged don't ussually become a problem, they can be fixed. DNA on the other hand is different, many combinations of damage can result in mutations which eventually (in high enough doeses) are lethal (ie you lose the ability to make certain protiens and then you die). 1 gamma ray going through you might cut a thousand strands but 50 lower energy gamma rays will cut mullions of strands. I think thats what he's agetting at. although it doesn't seem liek he had much of a clue on the how lower energy rays can be more damaging.

      • OK, IAAP (I am a physicist) and I'll tell you flat out that second order effects only become really significant when the radiation is VERY powerful, and can cause nasty showers. Most of the cosmic radiation showers don't come anywhere close to hitting the earth's surface, so this won't be an issue. Now if you were flying at 60,000 feet, who knows, it might almost be relevant, but even then I wouldn't count on it.

        You tend to get secondary showers when you have things like proton beams at huge energies hitti
        • OK, IAAP (I am a physicist) and I'll tell you flat out that second order effects only become really significant when the radiation is VERY powerful, and can cause nasty showers.

          I'll give you the same line: Which part of "sometimes" don't you understand? I was specifically thinking of space travel, not people on Earth.
        • the vast majority of cosmic radiation would be stopped by the atmosphere, magnetic field or no

          All the same, we still need the magnetic field to stop the solar wind from stripping away the atmosphere

      • Re:So Lemme Get This Straight.... (Score:1, Interesting)

        by Anonymous Coward

        Second-order effects very often swamp the first-order effects. This is one of those basic facts of mathematical thinking that is vital to understanding any sort of science,

        This is fully and entirely the opposite of how this phrase is used in science and mathematics. Talking about second and higher orders is commonplace, but once you start talking about second order or higher "effects," you are talking about terms that go to zero faster than the terms of lower order. For instance, if you take the squar

      • Well, the magnetic field deflects the charged solar wind (your minor nit is not so minor - solar wind and em radiation are 2 different things).

        Also, shielding is not the cause of secondary radiation from the high-energy cosmic rays. Typical such radiation (say, protons) couldn't care less about ozone - they would 'care' about 'hitting' nucleons and generating secondary showers, so ozone or oxygen is all the same. Secondary radiation is mostly bad because it's charged (muons), so in high-density materials (

  • Good slides from UW Aeronautics and Astronautics (Score:5, Informative)

    by joelparker ( 586428 ) <joel@school.net> on Saturday May 15, 2004 @02:37PM (#9162660) Homepage
    Good lecture slides on solar events in PDF [washington.edu]
    are from the Aeronautics and Astronautics [washington.edu]
    group at the University of Washington.

    They also have nice slides on airplane/spacecraft design,
    also in PDF here [washington.edu]

  • What does the fossil record show? (Score:5, Interesting)

    by beeplet ( 735701 ) <beeplet@gmail.com> on Saturday May 15, 2004 @02:43PM (#9162696) Journal
    Records of the field direction, frozen into sediments laid down on the seabed, show that the magnetic field has reversed hundreds of times in the past 400 million years.


    I would have thought that that alone would indicate that field reversals are not exactly "disasterous" for life on Earth. Poor for human health, maybe, but it's not like we're facing mass extinction.

    Actually, given that they're apparently able to identify eras of field reversal in the archeological record, I wonder if anyone has tried to correlate it with periods of extinction or rapid evolution? That would be more interesting to me - at least better than all of the speculation that seems to be going around.

    • Re:What does the fossil record show? (Score:5, Insightful)

      by bcrowell ( 177657 ) on Saturday May 15, 2004 @08:01PM (#9164215) Homepage
      I would have thought that that alone would indicate that field reversals are not exactly "disasterous" for life on Earth. Poor for human health, maybe, but it's not like we're facing mass extinction.
      I don't think it's that easy to read the fossil record and apply it to our situation. A species could easily get its population knocked down to 1/1000 of its former value, then recover over the course of a few centuries, without ever leaving a detectable trace in the geologic record. Also, it's often unclear why one species survived a mass extinction event while another went extinct, e.g., nobody knows why alligators and crocs survived the event that killed off the dinosaurs.

      Actually, given that they're apparently able to identify eras of field reversal in the archeological record, I wonder if anyone has tried to correlate it with periods of extinction or rapid evolution?
      I'm not a biologist, but IIRC, radiation-induced mutations are not a major driving force behind evolution. I think most evolution occurs simply by reshuffling the preexisting genes. And remember, there are plenty of chemicals in the environment that are mutagens. If radiation was a big factor driving evolution, it would be hard to understand most of the evolutionary history of life on earth, since most life on earth isn't terrestrial, and the nonterrestrial stuff (fish, underground bacteria,...) is shielded from radiation that comes from space. (Some radiation comes from the earth itself.) A lot of radiation doesn't penetrate very deeply, either, so it's a lot more likely to give you skin cancer than to mutate your sperm or egg cells.

      BTW, I believe there was no measurable increase in mutations among the kids of the Hiroshima and Nagasaki survivors.

      • > nobody knows why alligators and crocs survived the
        > event that killed off the dinosaurs.

        Hibernation is the answer in my opinion. The earth probably got very cold during the time immediatly following the apparent global blackout caused by the asteroid hit. Creatures that hibernate were able to survive as well as birds (therapod dinosaurs with feathers and warm blood). I would have to figure that the birds scavenged and migrated for much of the time during which the cold-blooded creatures perished.
    • it's not like we're facing mass extinction

      Actually the fossil record shows the trend of one mass extinction after another! ... although millions of years apart and not due to magnetic fields

  • Worried about your compass? (Score:5, Funny)

    by jgaynor ( 205453 ) <jon.gaynor@org> on Saturday May 15, 2004 @02:50PM (#9162734) Homepage
    "Phew! I was worried I will not be able to use my compass."

    Oh yeah! I forgot about my compass not working! Silly me - I was too busy thinking about the possible massive upsurge of CANCER . . .
  • After reading this, I think we'll be seeing at least one movie, and a mini-series on Fox:

    Not only has the magnetic north pole wandered by 1100 kilometres in the past 200 years, but its strength is dropping at a rate of 5 per cent a century. "This is the fastest decrease since the last reversal 730,000 years ago," Lesch says

    I do find it interesting, I wonder if it could happen in the next 300 years or so?

  • Don't buy compass stock just yet... (Score:4, Insightful)

    by Ayaress ( 662020 ) on Saturday May 15, 2004 @05:40PM (#9163491) Journal
    Just because the solar wind will help produce a magnetic field in place of the Earth's natural one doesn't mean it'll point in the right direction. That compass may be just as useless with this field as it would with none at all. How will you feel when your compass informs you that you're traveling straight up?
    • Just because the solar wind will help produce a magnetic field in place of the Earth's natural one doesn't mean it'll point in the right direction.

      I don't think they claimed it would solve the compass problem, only the radiation problem.

      BTW, how come it does not work on Mars, which has no significant magnatic field of its own?
      • The article didn't, but the Slashdot post did. Anyway, Mars also has no significant atmosphere of its own either. Of course, this raises the question of why it doesn't work on Venus, which has a very substantial atmosphere, but no magnetic field worth mentioning.
      • Mars does indeed have a significant magnetic field, it is just that it has several dozen north and south poles, which is the current theory about what will happen during the transition phase when the poles switch:

        At first the poles weaken in strength.

        New "North" & "South" poles start to appear in strage places, like in equatorial regions.

        For a geologically brief period of time there are dozens to hundreds of magnetic "poles" scattered throughout the planet.

        Eventually the number of poles start to drop, and the new magnetic "North" & "South" poles become more established and start to gain more strength. At this point the reversal is complete.

        Mars appears to have gone geologically dead during the middle of one of these pole reversals, so Mars is also being used to provide a "snapshot" as to what the Earth might be like in the next 500 years.
        • Mars does indeed have a significant magnetic field, it is just that it has several dozen north and south poles

          My recollection is that its magnetism is very weak compared to Earth. It took powerful sensors to find them.
          • that would make sense if there a so many...
          • It wasn't so much the strength, but with the very localized north & south poles (like I said, dozens of "poles", sometimes only 10 km apart.), it makes for a very different magnetic field than what you find right now on the Earth.

            Originally planetary astronomers were looking for a classical Magnetosphere like is found on the Earth and Jupiter, but Mars simply doesn't have that because it isn't organized on a planetary scale.

            An interesting side-effect to the paper suggested by the parent article is that planets may mean something more significant than simply a rock to anchor your building to. If a planetary body (like Mars or Veuns) can capture a portion of the solar wind and form a magnetic barrier to Cosmic Radiation, it might be more valuable than trying to make cities and settlements on smaller bodies that this effect wouldn't be nearly so strong, such as building in the Asteroids or even building Human constructed bodies such as the classical L-5 space habitats, at least until space born populations start becoming significant.

            Several people have suggested that Mars is a dead-end for human settlement due to the fact that it too is at the bottom of a signficant gravity well. It is nice to see that potentially some theories that might support a manned Martian presence are being brought forth.

            • No quite a free lunch (Score:3, Interesting)

              by cft_128 ( 650084 )
              The long trip to Mars will need strong shielding, just like a space station at the Eeath/Moon's L5 would need (not to mention the sheilding needed to get through the Van Allen belts [wikipedia.org]). Of course a long term habitat would be served nicely by the 'free' sheilding.
              • sheilding isn't really a problem we've been doing that since the 40's with Trinity and the Manhattan project, (which is one of the reasons that those anti-lunar people are nuts, we had the technology to sheild against radiation in the 40's and 50's in nuclear testing, but we couldn't do it in the 60's?)
                • sheilding isn't really a problem we've been doing that since the 40's with Trinity and the Manhattan project, (which is one of the reasons that those anti-lunar people are nuts, we had the technology to sheild against radiation in the 40's and 50's in nuclear testing, but we couldn't do it in the 60's?)

                  Shielding a bunker/lab on the ground versus shielding a spacecraft you have to propel to the moon is a very different proposal. The Apollo missions had carefully plotted courses through the thinnest areas

  • Your compass will still be obsolete (Score:3, Informative)

    by Transcendent ( 204992 ) on Saturday May 15, 2004 @09:48PM (#9164672)
    During the reversal, there will be some magnetic fields left, but will be more random and spiratic than usual. Your compass will still point somewhere... but that won't have any correlation to where north is.

  • Worth Noting... (Score:4, Informative)

    by CheshireCatCO ( 185193 ) on Sunday May 16, 2004 @04:07AM (#9165746) Homepage
    The idea that the atmosphere/ionosphere can be used to set up counter-currents to exclude the solar wind from the planet (or at least shield it a lot) isn't really revolutionary. It's possible that the Earth-magnetospheres people aren't talking to the planetary folks enough, but the latter have been thinking about this for years. When you wonder how the solar wind behaves when it encounters, say, Venus, you're in this regime. It's also the basic category that includes those ever-sexy critters, comets.

    I don't know that anyone has done a similar calculation for the Earth and if so if this new model is significantly different. But the basic idea has been out there. We covered it in my magnetospheres class 4 years ago and it was in the textbook well before that.

  • Nova recently had a show about this! (Score:5, Informative)

    by GooberToo ( 74388 ) on Sunday May 16, 2004 @08:34AM (#9166513)
    http://www.pbs.org/wgbh/nova/magnetic/
  • Reminds me of some weird all lyrics:

    "Every thing you know is wrong, up is down, left is right, and short is long."

    hehe
  • The reasoning sounds good, but the article doesn't address the fossil record at all. In layers of sediment laid down during magnetic pole reversals, hundreds of fossil species suddenly disappear and new ones appear. At least that's what I've read. Don't actual mass extinctions argue more strongly than theory?
    • The periodic mass extinctions don't usually coincide with magnetic field reversals. Field reversals are much more frequent than mas extinctions. The main body of empirical evidence for the field reversals are the alignment of magnetic domains in the ocean floor. However, the magnetic field described in this article would be weak and transient. It wouldn't have a fixed north and south. It would have multiple norths and souths, which themselves wouldn't be far more variable than the "normal" magnetic field.
  • I apologize if this got posted twice. This is a subject that has intrigued me, and while I cannot claim any expertise in the field, here is what I have gathered, info-wise, in answer to many of the common questions I've seen on here. I will try to reference my sources where possible, though some of this is coming from memory.

    How often does this happen?
    Over the last 15 million years, the trend has been 4 reversals every 1 million years. However, this is not periodic. You could have one every 250,000 y

Slashdot Top Deals

A physicist is an atom's way of knowing about atoms. -- George Wald

Close