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sage
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why does Earth's magnetic field flip polarity at regular intervals?does it have any effect on the biosphere. are we in the midst of a flip as a recent programme in discovery channel suggested?thak you.
I saw a mind bending program about this on television three or four months ago. I don't know if it was the same you saw. They presented the history of the flips as far as anyone understands them, and have, indeed, determined that we are on the verge of the next one, based on the history of variations in the local magnetic field that they have, which covers something like the last 300 years. Most of this is from the ship logs of people like Captain Cook who sailed the globe and kept strict records of the variations.sage said:why does Earth's magnetic field flip polarity at regular intervals?does it have any effect on the biosphere. are we in the midst of a flip as a recent programme in discovery channel suggested?thak you.
Yikes! It is entirely likely, then, that the show I saw was talking about an impending PME, and not a pole reversal. Pole reversals may also have been discussed and I confused the two.Andre said:Hold it, there are magnetic reversals, when North turns South etc, Those are relatively rare, the last few dozen million yars they have occurred with frequencies of about 700-800,000 years, the last one, the Matuyama - Brunhes boundery has happened some 780,000 years ago. There are also Paleao Magnetic Excursions, when the magnetic field collapses but recovers eventually. They last about 6000 years. Although the frequency of PME's is roughly 100,000 years, a correlation with "Ice Age" periods with about the same frequency is not apparent yet.
Zooby, was this the show? I also saw it. It's about reversal of the Earth's magnetic field.zoobyshoe said:Yikes! It is entirely likely, then, that the show I saw was talking about an impending PME, and not a pole reversal. Pole reversals may also have been discussed and I confused the two.
Thanks for catching that.
-Zooby
This looks very much to be what I saw. I came upon it by flipping through the channels, it caught my eye, and I didn't pay attention to the title. The show I saw had a lot of animated graphics of the magnetic field, which suggests the link you found is the same one.Evo said:Zooby, was this the show? I also saw it. It's about reversal of the Earth's magnetic field.
http://www.pbs.org/wgbh/nova/magnetic/
The notices are weekly now.sage said:any idea why i am not getting any notifications on email about new replies though i am subscribed to this thread. are the notifications on a weekly basis or instantaneous basis?
Actually, I just got an instant notification of sage's post.Evo said:The notices are weekly now.
sage said:i got the impression that the experiments with liquid sodium has so far been unable to generate a self sustaining magnetic field which is not good news for the dynamo theory. anyway let's hope further experiments show positive results. does anyone know of any model or simulation that shows that a self sustaining magnetic field can be generated by the rotation of the liquid iron core as proposed by the theory?
Later observations also showed that during the last tens of millions of years, the magnetic polarity of the Earth reversed many times, something that Blackett's prediction would never allow.
A magnetic field flip, also known as a magnetic pole reversal or geomagnetic reversal, is a process in which the Earth's north and south magnetic poles switch places. This means that the magnetic field that surrounds our planet flips in polarity.
Magnetic field flips are not a regular occurrence and do not happen on a set schedule. The last full reversal occurred about 780,000 years ago, but there have been partial reversals in between. Scientists estimate that full flips happen on average every 200,000 to 300,000 years.
During a magnetic field flip, the Earth's magnetic field weakens and becomes more chaotic. This can lead to increased exposure to solar winds and cosmic rays, which can have harmful effects on living organisms. However, there is no evidence that past magnetic field flips have caused mass extinctions.
The complete process of a magnetic field flip can take thousands of years. The weakening and reversal of the magnetic field can happen quickly, within a few hundred years, but the full flip can take up to 5,000 years to complete.
Currently, we do not have the technology to accurately predict when the next magnetic field flip will occur. However, scientists continue to study the Earth's magnetic field in order to better understand the process and potentially make predictions in the future.