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PostPosted: Sun Sep 04, 2011 23:56 
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Did anyone happen to see this most interesting BBC program the other day ?
BBC wrote:
Horizon - 2011-2012 - 4. The Core

It is available on the BBC IPlayer until 9:59PM Wed, 21 Sep 2011 at the following links.
http://www.bbc.co.uk/i/b0148vph/
http://www.bbc.co.uk/iplayer/episode/b0 ... _The_Core/

For centuries we have dreamt of reaching the centre of the Earth. Now scientists are uncovering a bizarre and alien world that lies 4,000 miles
beneath our feet, unlike anything we know on the surface. It is a planet buried within the planet we know, where storms rage within a sea of
white-hot metal and a giant forest of crystals make up a metal core the size of the Moon.

Horizon follows scientists who are conducting experiments to recreate this core within their own laboratories, with surprising results.

Broadcast on BBC Two, 9:00PM Wed, 31 Aug 2011 - Available until 9:59PM Wed, 21 Sep 2011 Categories Factual, Science & Nature - Duration 60 minutes

it showed how they can now tell how the center of the Earth is solid and about as large as the moon ! Also showed how the magnetic field is slowly changing and will likely swap around so Nth is Sth (as it were) - but they estimate that this will take about 700yrs.
Now this kind of change is apparently already effecting Satellites and they have to be turned off when they pass a magnetic field change ... (Southern hemisphere, and I think they said planes too had to make some changes too. I have concerns about the possibility of changes to the jet stream which will effect many many weather / climate patterns. I wonder if this is what really caused the dinosaur decline ?
Someone else I know pointed out that this would change cloud patterns that cannot be rectified....

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PostPosted: Mon Sep 05, 2011 11:52 
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Magnetic reversal.
Last happened about three quarters of a million years ago.
During the changeover the globe is subject to higher levels of radiation and ultra-violet light, animal life being subject to increased mutation as a result.
Results from the CERN experiment CLOUD seem to show that cosmic radiation leads to increased formation of aerosols, which may increase cloud formation....and reflect heat back into space....leading to a cooler planet.
Since the molten core would exceed the Curie point for iron I doubt that that is responsible for the magnetic field of the planet....
All good fun.

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PostPosted: Mon Sep 05, 2011 13:22 
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Since the molten core would exceed the Curie point for iron I doubt that that is responsible for the magnetic field of the planet....


But it is still conductive! I think the idea is that convection currents in the molton iron act as a form of dynamo. Essentially the earths magnetic field is generated electromagnetically. (like with an automotive dynamo there must be some residual field, perhaps in the outer crust where temperatures are below the curie temp, to "Kick things off" as it were but once the core movement starts generating its own field the process will be self sustaining and self amplifying)

The Interesting question is what is the source of the heat that is generating the convection currents??


The common assumption is that it (The heat) is the product of radioisotope decay, however a more interesting suggestion is that it might actually be being produced by urainium fission reactions at the earths core though this is not a generally accepted theory! (See http://en.wikipedia.org/wiki/Georeactor)

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PostPosted: Tue Sep 06, 2011 12:38 
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More likely potassium 40 decay.......
Not that it makes any difference....the pressure is some 4 million atmospheres at earth central....so no liquid anything.

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56 years after it was decided it was needed, the Bedford Bypass is nearing completion. The last single carriageway length of it.We have the most photogenic mayor though, always being photographed doing nothing


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PostPosted: Tue Sep 06, 2011 15:07 
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Magnetic North has always shifted slightly. When you look at nautical charts they typically have several little "compass" circles on them showing where magnetic North is at that location and at the time the chart was published. It then usually says something like "shifting 08' East annually" so you can work out where magnetic North is likely to be 5 years after the chart was published. Ships used to have to swap to their "Southern Hemisphere compass" as they crossed the equator (still do, in fact). If and when the poles swap over, the compass manufacturers will just have to remember to sell Northern Hemisphere compasses in Suthern Hemisphere boxes (and vice versa) but I'm sure that won't be the most serious effect of such a change! I'm told it's happened several times in the earth's history.


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