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Old 18-05-2007, 16:55   #166
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"Well, there is indeed one thing you would have to worry about (since it would kill you) during the pole reversal. During the reversal, the Earth would temporarily lose its magnetosphere. "

I'm definitely gonna put this on my list of cr*p to worry about. Right after Alien Invasion but well below Season 6 of American Idol which scares me a lot more...
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Old 18-05-2007, 20:07   #167
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Originally Posted by ssullivan
Well, there is indeed one thing you would have to worry about (since it would kill you) during the pole reversal. During the reversal, the Earth would temporarily lose its magnetosphere. No more pretty auroras... just deadly radiation beaming directly into the top of your skull.
Actually, the upside of earth not having a magnetic field would be that auroras would be visable every night all over the world. The downside would be a 0.14% increase in the number of new cancers world wide per year.

Also, some think that if earth was without its magnetic field long enough the planet's atmosphere would be stripped away. This would take millions of years... if at all.

From a sailing perspective this would make navigation more complicated without a compass and not being able to get star sights because of the auroras. Oh, and better grounding would be needed to keep Staint Elmo's fire out of the rigging and the electronics. Also, weather reports via SSB/Ham HF communication would be a thing of the past. Even Radar and VHF communications might not work all that well when ionized clouds are floating over the ocean surface.

However, a collapse of the earth's magnetic field is not expected for at least another millennium or so. I don't think I need run out a buy the new GPS compass and underwater communicator quite yet.
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Old 19-05-2007, 00:12   #168
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During the reversal, the Earth would temporarily lose its magnetosphere
No it wouldn't. The Earths Magnetic Feild is not electrical. It can't turn off and on. It is a permanent magnet. You can't just turn the magnet off. But for some reason the entire Earths core simply rotates or flips over.
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Actually, the upside of earth not having a magnetic field would be that auroras would be visable every night all over the world.
No it wouldn't either. The magnetic sheild around the earth is what bounces the solar wind off and the interaction is what causes the aurora.
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Also, some think that if earth was without its magnetic field long enough the planet's atmosphere would be stripped away.
You are quite right. The solar wind would simply blow the atmosphere away and in very short time, not as long as you think, and life as we know it Jim, would no longer exist. The atmosphere of Mercury was blown away in almost an instant when the Sun burst into life. However, that is mostly because it is s close, not even a magnetic field would be able to protect it.
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a collapse of the earth's magnetic field is not expected for at least another millennium or so.
Well now ya see, that's the problem. We are somewhat way over due.....maybe. Something like 70,000 years overdue. However, the cycle is on a very random fluctuation. Sometimes it is fairly precise, and then sometimes a very wide fluctuation occurs. Once again, many theories, no one really knows why the flip occurs and what triggers it. If it is internaly triggerd or externally triggered. Seeing as the Sun experiances a regular cycle, it is proven that the Sun has no influence.

Of course, I need to add an important statement here. My comments above maybe totaly wrong. I am only echoing one of many theories and one that I personly feel is more "on track", but NO ONE really knows. There are many theories, but a lot of the magentic feild is still a total mistry to Scientists.
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Old 19-05-2007, 02:19   #169
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Alan, it is my understanding that in the Earth the liquid metal that makes up the outer core passes through a magnetic field, which causes an electric current to flow within the liquid metal. The electric current, in turn, creates its own magnetic field—one that is stronger than the field that created it in the first place. As liquid metal passes through the stronger field, more current flows, which increases the field still further. This self-sustaining loop is known as the geomagnetic dynamo.

The so-called Coriolis force also plays a role in sustaining the geomagnetic dynamo. Our planet's spinning motion causes the moving liquid metal to spiral, in a way similar to how it affects weather systems on the Earth's surface. These spiraling eddies allow separate magnetic fields to align (more or less) and combine forces. Without the effects caused by the spinning Earth, the magnetic fields generated within the liquid core would cancel one another out and result in no distinct north or south magnetic poles.

The strength of our world's magnetic field has been diminishing for the past 300 years. The loss of strength could be an indication that a reversal is under way. This would be no surprise. On average, reversals of the Earth's magnetic field happen every 250,000 years. It's now been about 720,000 years since our last reversal.

A reversal usually takes hundreds or thousands of years to complete. A reversal begins with additional north and south poles appearing at the core. These additional poles can weaken the overall magnetic field strength. One such weakening has appeared beneath the South Atlantic Ocean. A collapse of the main dipole field can last for up to 10,000 years during a reversal.

However, there is no firm evidence that the many magnetic field reversals that have taken place throughout our planet's history have coincided with or triggered extinctions.

Auroras occur when electrons and protons hit the upper atmosphere. The result is a bright glow that can last anywhere from a few seconds to a few hours. Oxygen in the atmosphere above 150 miles glows red when exposed to fast-moving particles, while oxygen below 150 miles appears yellow-green or green, the brightest and most common auroral hue. The aurora gets its blue color from nitrogen below 60 miles. During a magnetic field reversal, which can take hundreds or thousands of years to complete, these dazzling natural light shows would be visible every night of the year.

Enjoy the show!
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Old 19-05-2007, 09:05   #170
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Old 19-05-2007, 14:22   #171
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Earth the liquid metal that makes up the outer core passes through a magnetic field,
One theory. The other theory is that the core is rotating one way and there is another outercore rotating the opposite. The effect is a dynamo. The reason for the seemingly different rotations is due to nuclear forces deep in the core. These have been able to be reproduced in a special nuclear reactor. The two opposing "spins" creat a Dynamo effect and produce the electric field. Although still only a theory, this theory does better explain the imense electrical flow generated and the resulting magnetic feild. Otherwise, it is considered difficult that the rotation of the core alone is enough to produce such a strong feild.
What ever is happeing down there and what ever the affect and effects we see, the big thing to me is that it shows just what a miricle this place we live on is. The smallest change in anything on this Rock, can upset such a fine balance. But more to the point, the fine balance that is sustained is nothing short of a Miricle.
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Old 20-05-2007, 07:01   #172
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hmmm ...
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Old 20-05-2007, 21:01   #173
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Originally Posted by Alan Wheeler
No it wouldn't. The Earths Magnetic Feild is not electrical. It can't turn off and on. It is a permanent magnet. You can't just turn the magnet off. But for some reason the entire Earths core simply rotates or flips over.
I asked a physicist friend about this. Specifically, I wondered how fast the poles were moving across the surface of the earth -- e.g. if the north and south poles switch places in a few weeks, then the north magnetic pole has to be moving south at hundreds of miles per day. It would be interesting to have your compass point toward Alaska one day, Hawaii a few days later, Polynesia a few days after that, etc. He said the geologic evidence shows that it doesn't do that. The magnetic field drops to zero and then increases again with the opposite polarity. Unfortunately, I don't remember what he said about how long that takes.
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Old 21-05-2007, 00:38   #174
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"Unfortunately, I don't remember what he said about how long that takes."

I certainly hope I'll have time to tack...
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Old 21-05-2007, 16:27   #175
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I faintly remember reading somewhere that it could happen in as little as 50 to 100 years. (Not necessarily 50 to 100 years from now, just that the interval could be that short.)
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Old 22-05-2007, 00:48   #176
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I just looked at the "Heartland Institute" web site.....(post 161) and l was gob smacked. They have a whole section on pro cigarette smoking. Seems Al Gore was right !!
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Old 30-05-2007, 14:30   #177
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We are having Global Warming today. Finally, we get a drying spell. We've been waiting since November. It's suppose to be warmer tomorrow. :cubalibre

The sailing's not much good though.
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Old 30-05-2007, 15:16   #178
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We are having Global Warming today. Finally, we get a drying spell. We've been waiting since November. It's suppose to be warmer tomorrow. :cubalibre

The sailing's not much good though.
Come on Del, you put that in the oven didn't you.
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Old 30-05-2007, 15:58   #179
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Originally Posted by delmarrey
We are having Global Warming today. Finally, we get a drying spell. We've been waiting since November. It's suppose to be warmer tomorrow. :cubalibre

The sailing's not much good though.

Delmarrey,
I'm going out this evening for a well deserved sail, as I've been splitting firewood all day.

We usually have great conditions for sailing up here, as we're North of the convergent zone and South of the Straits.
You just live in the wrong place!

And yes, I am under sail here.

Steve B.
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Old 30-05-2007, 18:42   #180
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Come on Del, you put that in the oven didn't you.
Actually, NO!
It got 3 degrees warmer after I took the picture. This IS in the sun BTW. In the shade? Well, I'll have to wiat until the weather report for the day.

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We usually have great conditions for sailing up here, as we're North of the convergent zone and South of the Straits.
You just live in the wrong place!
You live right at the end of the Strait's, don't you? That's one of the windest anchorage's I've spent the night, right by Coupeville..........._/)
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