Science Daily: Auroras In Northern And Southern Hemispheres Are Not Identical.
ScienceDaily (July 24, 2009) — Norwegian researchers have shown that the auroras in the Northern and the Southern hemispheres can be totally asymmetric. These findings contradict the commonly made assumption of aurora being mirror images of each other.
The study was performed by PhD student Karl Magnus Laundal and professor Nikolai Østgaard at the Institute of Physics and Technology at the University of Bergen.
"The aurora is produced due to collisions between the Earth’s atmosphere and electrically charged particles streaming along the Earth’s geomagnetic field lines. – Since these processes occur above the two hemispheres, both the Northern and the Southern light are created. So far researchers have assumed that these auroras are mirror images of each other, but our findings show that this is not always the case," professor Nikolai Østgaard says.
The researchers at the University of Bergen have used data from the two NASA-satellites IMAGE and Polar to examine the Northern and the Southern light. In the Nature letter they present several possible explanations to the unexpected result.
"The most plausible explanation involves electrical currents along the magnetic field lines. Differences in the solar exposure may lead to currents between the two hemispheres, explaining why the Northern and the Southern light are not identical," PhD student Karl Magnus Laundal says.