--- In methanehydrateclub@y..., foryeshua1@j... wrote:
> David, I do not understand what you mean when you say that the magnetic
> field is pointing North or South. And why this puts a lid on
> geomagnetic activity. Walter
As the solar wind propogates out from the sun, it carries a magnetic
field along with it. Don't ask me the physics behind exactly how that
works! Anyway, its called the Interplanetary Magnetic Field (IMF),
and it can have either a north-pointing or south-pointing polarity.
Did you know that every compass on Earth is wrong? They're marked 180
degrees off. What we call the south pole is actually Earth's magnetic
NORTH pole! Earth's magnetic field lines actually emerge from the
south magnetic pole and reenter the Earth at the north magnetic pole.
That makes the south pole, well, the north pole!
An IMF that has a north polarity will reinforce Earth's own magnetic
field, since the magnetic field lines will be flowing in the same
direction as Earth's. That will lessen geomagnetic activity. A
south-pointing IMF, however, will "collide" with and weaken Earth's
magnetic field. That lessens Earth's magnetic shielding, and makes
the Earth more vulnerable to the high speed solar wind.
When high speed solar wind strikes the Earth's magnetic field lines,
it causes electrons to be accelerated along the field lines. They
come crashing down at the magnetic poles and spread out, energizing
the upper armosphere. The result is....aurora!