Re: Question: what is the SAA on the map showing orbital paths?

In article <11f8tk5285a3t47@xxxxxxxxxxxxxxxxxx>,
Pat Flannery <flanner@xxxxxxxxxx> wrote:
>>It's very slowly drifting west - given time it'll become the South
>>Pacific South Atlantic Anomaly, somewhat confusingly...
>
>What that implies is that the thing causing it is beneath the crust of
>the Earth, and is floating in the magma of the outer core- which makes
>one wonder what the hell the thing causing it _is_ exactly?

It's moving because Earth's magnetic field is changing slowly. The SAA
isn't due to an irregularity in the field -- it's there simply because the
field is off center, and therefore the Van Allen belts are off center too.
It's moving because the field as a whole is moving.

Just *why* the field is moving is a bit less clear. It's also changing in
other ways, which are even less understood. One theory is that we are in
the early stages of a field reversal, and we can expect the field to
weaken and become confused as the reversal proceeds. (A reversal probably
doesn't involve the field dying down to zero and then building up again
pointed the other way; more likely, the intermediate phase is a somewhat
weak field with a complicated, confused structure, out of which order
slowly re-emerges.)
--
No, the devil isn't in the details. | Henry Spencer
The devil is in the *assumptions*. | henry@xxxxxxxxxxxxx
.

Relevant Pages