Re: Iron Crystal Core? [was "earth/moon relationship"]
James Rogers (jamesr@best.com)
Wed, 29 Oct 1997 12:14:35 -0800
At 11:06 AM 10/29/97 -0800, Geoff Smith wrote:
>
>I seem to remember reading an article that stated that the very centre of
>the core was a massive crystal(I think of iron) How was this determined?
>Well, don't quote me on this, but I think either someone shot some time of
>EM radiation through the earth and measured it's distortion on the other
>side (of course, the radiation would be altered differently depending on
>how it entered the grain of the crystal) Hmm... that doesn't sound like a
>very likely scenario now that I think about it. How about this: when an
>earthquake occurs on the other side of the planet, you measure how long it
>takes to go through the diameter of the earth. The time it takes should
>be influenced by the direction the shock wave passes through the crystal.
>Apparently, the arrangement of the domains of this large iron crystal
>explain the earth's large magnet field. Also, one could explain pole
>shift(not the kind Danny was talking about!) by the inversion of this iron
>crystal, which might be induced by some external magnetic field... a large
>metallic asteroid? Sorry I'm being so vague... has anyone else read the
>article to which I am poorly alluding?
The determination that the core may be a large iron crystal was due to the
anisotropic propagation of seismic waves through the core. The
differences in propagation speeds were consistent with the propagation of
seismic waves through large crystals. Additionally, there was a high
correlation between the collected seismic propagation data, and the data
generated via a computer model assuming a single large iron crystal in a
HCP lattice. An HCP lattice is the most likely structure for an iron
crystal (which also exhibits FCC and BCC lattices) under the conditions
expected in the core.
-James Rogers
jamesr@best.com