Re: Earth's Magnetic Field

[Ludwik Kowalski <KowalskiL@MAIL.MONTCLAIR.EDU>]

Lee Lerner, saying  "I hope this gives you a good start", wrote:

> ... The Earth's magnetic field is generated as the outer liquid
> core with charged ions (i.e., electrical current) moves around
> solid inner core. ...

I have no trouble of accepting the idea that B is generated by
some kind of a current. But the nature of this current, and what
causes it, present conceptual problems. It is a "mystery" to me.

Yes, ions in the hot liquid core must be present due to high
temperature (and who knows what else). But macroscopically
the highly compressed "lava kind" stuff must have as many
+ as - ions. Thus, unless they move in the opposite direction,
the net current resulting from a circulation of liquid matter
around the solid core should be zero.
Ludwik Kowalski
.....................................
> My geophysics might be a bit rusty but I believe that
> seismographic S waves reflect a pattern consistent with an
> Earth core composed of a liquid outer core surrounding a
> solid inner core.  The core is believed to be comprised
> mostly of Fe and Ni.   The Earth's magnetic field is
> generated as the outer liquid core with charged ions (i.e.,
> electrical current) moves around solid inner core.

> There have been scholarly observations of  the earth's
> magnetic field for almost 500 years. Sir William Gilbert
> published the first treatise on the earth's magnetic field
> ( De magnete).  Gilbert showed that the reason compass
> needles point toward the earth's north pole is because the
> earth itself appears to behave as a large magnet.  Gilbert
> argued that the earth's magnetic field is roughly equivalent
> to that which would be generated by a bar magnet located
> at the center of the earth and oriented along the earth's
> rotation axis.

> Later in the mid-nineteenth century, Karl Frederick Gauss
> confirmed Gilbert's observations and also showed that the
> magnetic field observed on the surface of the earth could
> not be caused by magnetic sources external to the earth, but