BibSonomy ::  concept ::

The mysterious aurora shining beautifully and colorfully in the night sky is a phenomenon occurring in the upper atmosphere over the north and south polar regions. The aurora often brightens suddenly around midnight and expands explosively while it moves violently. This intensive auroral activity is called the auroral breakup (auroral expansion). When the event occurs, a huge current from several hundred thousand to several million amperes runs in the upper atmosphere, causing geomagnetic disturbance. In the region called the magnetosphere where the Earth’s magnetism governs (Fig. 1), there are also violent changes of electromagnetism and plasma (i.e. charged gas)