| DESCRIPTION:
The earth sits in the magnetic field of the solar wind,
which drags out the magnetic field of the sun to the
neighborhood of the earth. The magnetic field lines
in the polar regions of the earth connect to the interplanetary
magnetic field lines, which are being carried past the
earth away from the sun at high speeds by the solar
wind. When the interplanetary magnetic field is southward
(as is the case here) it can connect easily to the earth's
magnetic field, which emerges from the south geographic
pole of the earth. Energy from the solar wind flow then
goes into stretching the reconnected field lines into
the "magnetic tail" of the earth. Eventually
those field lines "break" and snap back toward
the earth on the nightside. It is this process transferring
solar wind energy into magnetic energy and thence into
energy flowing into the earth's atmosphere as the magnetic
field lines "snap" that drives the aurora.
The aurora occur at the feet of the "last closed
field line", which defines the auroral oval.
|
|
