This site defines the magnetosphere as the combination of the earth’s magnetic field and the solar wind. This makes Van Allen Belts, also called by the prosaic name “radiation belts,” a part of the total magnetosphere.
Here’s a cite for all those asking for one.
From the link:
High-resolution images of the geomagnetic field taken in 2000 by the Oersted satellite, combined with similar images taken in 1980 by the Magsat satellite… have identified patches of reversed magnetic flux concentrated … beneath the southern tip of Africa…[and] in the north polar region. Growth and poleward migration of the reversed-flux patches can account for almost all of the decrease in the dipole field in the past 150 years. …[T]he geological record shows that the magnetic field intensity has oscillated in the past without actually reversing its polarity. But the rapidly evolving reversed-flux patches suggest that an attempt at reversal may be underway…[and] can explain why [dipole] polarity reversals, once initiated, can happen over only a few thousand years.
Will someone puh-leeeze think of the auroras !!!
There was recently an episode of Nova on PBS that discussed this very issue in detail. The website has some rather good explanations of the phenomenon and some nice interactive illustrations.
How’s that work, exactly? Our polarity switches and Orion starts dressing to the right? :dubious:
Uh…no.
The solar “wind” is not exactly the hurricane force you’re invisioning. It is merely a very dispersed stream of charged particles (mostly hydrogen). As such, it has minimal kinetic force. After all, the satellites and probes we send around the solar system don’t blow away. Our gravity is much more than a match than a few pitiful hydrogen particles.
Venus, incidentally, is much closer to the sun, has weaker gravity, and a much thicker atmosphere. While I can’t speak to Venus’s magnetic field, it seems logical that it too would wax and wane like Earth’s, and yet it still retains its thick air.
Uh …yeah.
http://science.nasa.gov/ssl/pad/sppb/edu/magnetosphere/mag4.html
Our neighboring planet, Mars, which has little or no magnetic field, is thought to have lost much of its former oceans and atmosphere to space. This loss was caused, at least in part, by the direct impact of the solar wind on Mars’ upper atmosphere. Our other close planetary neighbor, Venus, has no appreciable magnetic field, either. Venus is also thought to have lost nearly all of its water to space, in large part owing to solar wind-powered ablation.