Ok... My question is and i know everything there is to know on the subject apart from the true name of it... Now it happened to Mars and someday will happen to Earth, it's when the magnetic poles begin to switch or swap if you will, the planet at question loses its atmosphere and once the poles have switched the atmosphere returns, Can anyone help..

Matt a.k.a Xeion

xx

I could be wrong, but his happens to Earth about every 200,000 years, and to the best of my knowledge the atmosphere has never been stripped away.

No. I can not help... Magnetic pole flip has little or nothing to do with atmospheric lose. The two are not related.
Gravity holds the gasses that make up a planets atmosphere. Only a massive solar outburst could sweep away a planets atmosphere.
The polarity of a planets magnetosphere can be affected by solar outbursts and reactions with solar winds of the ionized particle stream. The iron core of Earth is rotating at a different rate as the mantle and thus a magnetic field of some considerable force is established. It will not and can not eject our air.

I believe Biz is correct.

Not only that, but our magnetic poles move all over the place even in our short lifetimes.

I don't think a complete shift would have any effect on us whatsoever. Negetive is still negetive, and vice/versa.

But as far as i know Venus has no magnetic field, and is exposed to a greater solar wind than Earth and Mars and yet keeps a thick atmosphere of carbon-dioxide and other gases?

As to the loss of atmospheric gases on Mars due to the loss of it's magnetic field, I believe the current theory is this took millions of years and the periodic magnetic pole swaps on earth may last a thousand years at most, (not enough time to loose an atmosphere).

What are the theories about the effects of the 'flip' on the protection we have from the magnetic field?

Will we be effect by 'stuff' that we aren't exposed to now?

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Good NOVA documentary that covers this: Magnetic Storm.

http://www.pbs.org/wgbh/nova/magnetic/

http://www.amazon.com/NOVA-Magnetic-...0924559&sr=1-1

And, during that slow process, it's not like the magentosphere goes away, or is neutralized somehow. Instead it's like the two dominant poles become several and then many and several and finally two again.

NASA Feature: Earth's Inconstant Magnetic Field

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Certainly a magnetic field reversal and some loss of atmosphere can be related, but one should not exaggerate the effect. Venus has no intrinsic magnetic field at all, as has already been pointed out. Yet its massive atmosphere shows no sign of going away any time soon. The solar wind interaction with the upper atmosphere of Venus does strip away some of the atmosphere, but only the very high velocity tail of the thermal distribution. Even billions of years of such an interaction could not strip away the whole atmosphere. The main reason for that is that Venus is a fairly substantial planet, with 81.5% of Earth's mass, and plenty of gravity. And since the atmosphre of Venus is 96.5% heavy CO₂, it doesn't go anywhere.

Mars also has an atmosphere mostly made of CO₂ (95.3%), and like Venus, it has no intrinsic magnetic field. But its mass is only 11% of Earth's, and that's a big enough difference to count. It's a good bet that Mars lost much of the atmosphere it might once have had, primarily because its low mass could not hang onto it. So Mars would have lost much of its atmosphere, even if it did have a magnetic field. But being without one allows the solar wind to directly impact the upper atmosphere, increasing the rate of loss.

Earth has more mass than Venus & Mars combined, so it is most capable of gravitationally holding an atmosphere. Earth also has a substantial intrinsic magnetic field, which fends off the solar wind, preventing it from directly impacting the atmosphere, except at the poles where the aurorae are generated by solar wind interactions in the very high atmosphere.

If Earth were to lose its magnetic field altogether, it would still be rather more retentive of its atmosphere than Venus, since the solar wind is weaker at Earth than at Venus, and Earth is so much more massive. But a magnetic field reversal is a transitory event. The reversal will see energy transfer from the main dipole to higher multipoles, presenting an apparently weaker magnetic field, and enabling the solar wind to more directly impact the upper atmosphere. The result will not be any substantial loss of atmosphere, but will be an enhanced background radiation field at the surface of Earth, due to increased solar wind particle impacts on terrestrial atmosphere particles. But I don't think we can predict how much more radiation there will be at the surface, and its biological effect, without a detailed model of the reversal process, which we don't yet have (Glatzmaier's simulations only show in general how the process works, but should not be considered detailed predictions of how it will happen on Earth).

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A magnetic reversal dosent completely cancel out the Earths field. All the reversal does is have the dipole field go away and then come back reversed. The quadropole and octopole moments will still remain.

All this is a bit irrelevant to the OP tho. Basically, even if the Earth completely lost its magnetic field, all that it would do to the atmosphereic loss rate would change it from almost zero to very slightly more than almost zero.

I have a question though: why do magnets reverse their poles?

From what I gather the Earth's magnetic field is 'electromagnetic' caused by swirls of liquid under the crust. Like a whole bunch of storms creating static electricity to generate a 'combined magnetic field'. There are many small pole pairs. Every once in a while the patterns change drastically, amplify each other, and do a swap.

The links posted by 01101001 will go into detail on this.

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((,.-' ((,/

Ok... Mars has no magnetic field because if the poles switching this has been proven! But not only did it lose its magnetic feild, and gravity by over half its orignal gravatational pull but also its atmosphere now if im not wring if it happened to Mars it could hapopen to Earth , seeming though Earth is a much more delacate and dense planet than Mars. Um... Mass doent come into it when concerning a atmosphere if MArs could hang on to its atmosphere for over 4 million years why not 4 more.... so infact its not the lack of mass it is infact the polatrties switching and getting caught in the merguary, so the poles swtiching play a massive act on the atmosphere and also the core resistance to the inner core would also increase by 85% if the poles did switch, this means the gravity of the Earth would dramtically drop. The atmosphere would therefore not be pulled in by the earth and (mass has nothing to do with iut alothough it does increase the amount of gravirty) beacuse with no centreal magnetic implluse from the centre of the Earth how would the atmosphere be able to sustain its self in a position of refelx if nothing is there to support it!!!?


Matt
xx

Wow.

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Translation, please?

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Mars may have had a dynamo at one time, but from the evidence hasn't had one for about four billion years. Earth shows no evidence of losing its dynamo any time soon (many millions of years), regardless of pole changes.

Is this a claim? If so, this would be more appropriate for the ATM forum. There is no evidence that the mass of Mars has changed, but it has always been far less than that of Earth, and it never could hold an atmosphere as well as Earth. That made solar wind erosion more significant for Mars than it ever would be for Earth.

Mars could have held onto a significant atmosphere for far longer than four million years. Billions of years (especially given the likely higher solar wind in the sun's early days as well as impact erosion back then) is another matter.

Yes, this is sounding like an ATM claim and not a question. No, the Earth's magnetic field isn't going to affect the Earth's gravity.

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Van Rijn:
Much respect for attempting to decipher Xeion's post.
With the spelling and grammatical errors I got lost after the first sentence.

Atmospheric loss rate is by far mostly determined by gravity and temperature. Unless a molecule can travel faster than escape velocity, it is stuck. On Earth, only atomic hydrogen, molecular hydrogen and helium can get fast enough to escape in relatively short time spans.