posted on Aug, 5 2009 @ 02:01 PM
An earlier thread (www.abovetopsecret.com...
) discussed the pressure representation of the
Real Time Magnetosphere Simulation
but pressure is only part of the interaction
between the solar wind and the magnetosphere. There is another part of the simulation which catches a lot of attention, the magnetic field
representation. The red and blue lines represent magnetic lines of force found within the Earth's magnetic field. To get an idea of the scale we are
looking at, the loops on the left, the sunward side, are reaching out to a distance of about 50,000 miles from Earth's surface.
The solar wind carries with it its own magnetic field (the Interplanetary Magnetic Field), left over from when it left the surface of the Sun. When
the IMF encounters the Earth's field some complex interactions take place. Close to the Earth, where the Earth's field is stronger, the IMF is not
strong enough to have much influence and the Earth's field maintains is toroidal shape. Farther out the IMF dominates, dragging, stretching, and
twisting the weaker field of the Earth.
The IMF is not constant. It changes in strength and polarity (the north/south) orientation. It is these changes which produce the changes in the
magnetic field lines of Earth's magnetic field. The ACE satellite (which provides the data for the simulation) measures several aspects of the IMF
but we are primarily concerned with the Bz component. This is the one that is oriented in the same plane (roughly) as the Earth's magnetic field.
When the IMF has a northward orientation (the same as Earth's) the Earth's magnetic field repels the Sun's field. When the IMF has a southward
orientation the two fields can connect through a process called magnetic reconnection
The stronger the Bz component, the stronger the connection or repulsion. This can be seen very clearly in the simulation. When there is a southward
value in the Bz component the lines of force take on a splayed appearance. They are joining with the IMF and streaming far out into interplanetary
space. When there is a northward value in the Bz this connection does not occur.
The lines of force are always shaped by the solar wind. With a southward Bz they hold hands with the Sun's field. With a northward orientation they
keep to themselves. With a southward orientation we see the red and blue lines separating as they connect with the Sun's field instead of themselves.
When we see the magnetic field lines forming a tight ball it does not mean the magnetosphere is collapsing, it means that it is not interacting with
the solar wind as much. It means it is reverting to it's "natural" shape, the shape it would have if there were no solar wind at
Here is an example of the effects of a southward orientation:
Here is an example of a northward orientation:
[edit on 8/5/2009 by Phage]