Talk:Earth's magnetic field/Archive 2

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Magnetic field affects charged particles, NOT ultraviolet radiation!

As far as I understand, Magnetic field deflects only charged particles, but UV is not affected. Am I correct? If so, please alter the article. Dimacq (talk) 23:15, 26 February 2010 (UTC)

The statement has a reference supporting it. If you know of a better reference, supply it and make the change. Thegreatdr (talk) 23:18, 26 February 2010 (UTC)
The reference does not mention magnetic fields and is being used erroneously. I removed that sentence. Crumley (talk) 02:46, 28 February 2010 (UTC)

Generating Electricity

Is it possible to generate electricity at the Earth's magnetic North/South poles?(long duration electric airplanes could navigate within a narrow "recharging zone" to stay aloft), I recall NASA astronauts experimenting with a Italian built "tether" that briefly generated current before the line snapped.Jalanp2 (talk) 19:25, 2 September 2010 (UTC)

You could use the Earth's magnetic field to generate electricity anywhere from the poles to the equator, but it would

not be enough to keep a plane aloft. Crumley (talk) 15:12, 4 September 2010 (UTC)

Radial vs tangential

This entire article never mentions that it pretty much only describes measurements of the tangential magnetic field (the one that drives compasses) and not the radial component, which is about 100-1000 times stronger. Here's some nice illustrations and calculation on the radial component. SamuelRiv (talk) 23:42, 9 February 2011 (UTC)

You need to read the article more carefully - like the part where it says that the magnetic field is straight down at the North Magnetic Pole. Also, the radial field is zero at the geomagnetic equator (where blue meets yellow in the plot your link points to), so it could hardly be 100-1000 times stronger than the tangential field! On the other hand, your confusion may be a sign that the writing in this article needs improving. RockMagnetist (talk) 20:36, 12 October 2011 (UTC)

Statistics

Why can't we have up-to-date statistics on the magnetic field? I propose the following information be added:

  • Strength (in Ampres per meter)
  • Current (in Ampres)
  • Length of circuit (in meters)

I'm not too keen on electrical physics, but I think this is a start.LutherVinci (talk) 12:33, 26 May 2011 (UTC)

The strength is given in B-field units (teslas). While the field is mainly due to currents in the Earth's outer core, we do not know what the currents are, and it is meaningless to talk of a length of circuit because the currents occupy a volume. RockMagnetist (talk) 20:29, 12 October 2011 (UTC)

Organization

This page is really disorganized. I have added a WP:todo box with my suggestions for organizing it. RockMagnetist (talk) 15:36, 4 October 2011 (UTC)

Merge discussion

There is a section in Geomagnetic reversals, titled Future of the geomagnetic field, which has nothing to do with reversals. It would make sense to merge that section with this article. There is already some overlap between it and the section on secular variation. RockMagnetist (talk) 18:24, 17 October 2011 (UTC)

The figure could stay behind to illustrate a new section on excursions. RockMagnetist (talk) 19:35, 17 October 2011 (UTC)

Inclincation

The inclination or dip is the deviation from vertical. WRONG ! The inclination or dip is the deviation from the horizontal. — Preceding unsigned comment added by 124.169.87.193 (talk) 14:25, 8 December 2011 (UTC)

Thanks for pointing that out. Did you know that you can edit pages yourself? RockMagnetist (talk) 15:32, 8 December 2011 (UTC)

InfoBox

The intensity of the earth's magnetic field needs to be mentioned in the first paragraph OR make an infobox on the right hand side.Nscozzaro (talk) 22:51, 22 January 2012 (UTC)

Magnetosphere protection

The intro currently ends:

"The region above the ionosphere, and extending several tens of thousands of kilometers into space, is called the magnetosphere. This region protects the Earth from harmful ultraviolet radiation and cosmic rays."

Since the magnetic field does not affect ultraviolet light (even if UV light is attenuated in the same region which I don't know) we shouldn't imply it by mentioning UV in the intro of this article. Shouldn't we mention that the magnetic field protects from charged particles in the solar wind? RJFJR (talk) 20:36, 24 January 2012 (UTC) I went back and struck the section on solar wind now that I just read our article about cosmic rays and see that charged particles in the solar wind are considered cosmic rays. RJFJR (talk) 20:40, 24 January 2012 (UTC)

The magnetosphere indirectly protects the Earth from ultraviolet rays. See Earth's magnetic field#Importance. RockMagnetist (talk) 21:33, 24 January 2012 (UTC)
That is really saying the magnetic field is protecting the atmosphere from erosion. May be we should say that. RJFJR (talk) 21:45, 24 January 2012 (UTC)
Feel free to modify it. RockMagnetist (talk) 21:58, 24 January 2012 (UTC)
I changed it to "This region protects the Earth from cosmic rays and the atmosphere from being stripped away including the ozone layer that protects the earth from harmful ultraviolet radiation." RJFJR (talk) 17:03, 25 January 2012 (UTC)
Thanks. I reworded it a little because it might seem odd that we are worrying about the ozone layer if the whole atmosphere is being stripped away. It would take billions of years to strip away the entire atmosphere but probably much less to destroy the ozone layer. RockMagnetist (talk) 17:48, 25 January 2012 (UTC)

(Future) Please use consistent units when talking about the same thing, especially within a paragraph!

The last paragraph under "Future" tells how the magnetic north pole has been drifing at different rates over the last century or so. Different sources may give different units, but whoever writes or cleans up the paragraph should convert them all to the same unit. The pole is drifting "with a presently accelerating rate—10 km per year at the beginning of the 20th century, up to 40 km per year in 2003,[29] and since then has only accelerated.[30] In the last decade magnetic north was shifting roughly one degree every five years." The earlier figures should be converted to degrees (or decimal fractions) per year, or the last one converted to km per year. Otherwise there's no easy way to tell how the current rate of change is different from the earlier figures. Benbradley (talk) 19:03, 22 March 2012 (UTC)

I checked the source for the latter figure, and it is based on a newspaper account that is too vague to be useful. It is really referring to magnetic declinations everywhere, not the movement of magnetic North, and it implies that the latter depend on the former, which is not true. It seemed better just to remove the offending statement. RockMagnetist (talk) 21:42, 22 March 2012 (UTC)

Core Conductivity

Any ideas on where the recent Nature letter to the editor which uses first-principles calculations to come up with substantially higher electrical conductivity than usually assumed should be referenced? Dan Watts (talk) 03:54, 22 May 2012 (UTC)

Inner or outer core? The reference could go in Earth's magnetic field#Earth's core and the geodynamo, but only in the context of quantitative numerical models of the dynamo. That would take some writing. You could put the reference here for future contributors; and you could also look into adding it to Inner core or Outer core, whichever is appropriate. RockMagnetist (talk) 04:11, 22 May 2012 (UTC)
Inner core.[1]
Dave Gubbins strikes again! Thanks for the reference. RockMagnetist (talk) 14:57, 22 May 2012 (UTC)

Tilt of geomagnetic dipole

I changed the tilt of the dipole back to 10°. I have seen that figure 11.3° somewhere, but it is not up to date. As of 2010, it was at 9.98° (see "Where are the magnetic poles?" in the citation I added). RockMagnetist (talk) 15:33, 15 July 2012 (UTC)

Earth's core and the geodynamo

The concepts about the motion of charges, as an underlying requirement for the article's calculations to be valid, would be obvious to any person versed in the physics of electromagnetism. The source of those moving charges is not addressed elsewhere in the article. I stated certain mechanisms for current generation that have been mentioned in the literature, and provided references. To say that my contribution amounts to vandalism because Mr. RockMagnetist did not like my references is petty, lazy, and is like throwing the baby with the bath water. If Mr. RockMagnetist dares to be constructive instead of destructive by deleting everything I wrote, he should enrich the article by providing more references (or even, references negating what I say, if he can find any). If even basic notions of electromagnetism need to be referenced everywhere in the article then, most of the article would need to be deleted according to Mr. RockMagnetist. — Preceding unsigned comment added by 98.217.147.183 (talk) 00:48, 10 December 2012 (UTC)

Since the origin of the currents is explained at the beginning of this section, the need for further explanation is not "obvious to any person versed in the physics of electromagnetism." My edit summary referring to citations is a polite way of saying that you are wrong. If you can find references that actually support your statements, then you can consider adding the material back. RockMagnetist (talk) 01:09, 10 December 2012 (UTC)
Sorry for labelling your edit "vandalism". I use Twinkle for many of my messages and sometimes I'm careless about the choice of message. I do believe your edits are in good faith. RockMagnetist (talk) 05:22, 10 December 2012 (UTC)

I see you have added a revised paragraph with new citations. The references do not support the idea of remanent magnetization in the mantle providing the seed field for a dynamo; in fact, in page 3 of his thesis, Livermore states that "The idea of permanent magnetism (the only form known at that time) suffered a fatal blow when it was realised that almost all of the Earth’s interior was too hot (above its Curie temperature) to retain its magnetisation". However, I now see what you're driving at. It is true that a dynamo needs a "seed" field to get started; but once the dynamo has started it doesn't need any further input. I have some good references on that, and I'll add some material. RockMagnetist (talk) 05:38, 10 December 2012 (UTC)

  1. ^ Pozzo, Monica; Davies, Chris; Gubbins, David; Alfè, Dario (2012), "Thermal and electrical conductivity of iron at Earth's core conditions", Nature, 485 (7398): 355–358, doi:10.1038/nature11031, retrieved 2012-05-22