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Published online 24 July 2008 | Nature | doi:10.1038/news.2008.982
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Aurora's source found by string of satellites
NASA's Themis mission finds the trigger for polar light show.
Five NASA satellites named after Themis, the Greek goddess of justice, have finally revealed the trigger behind the brilliant auroras that dance across the polar skies.
The Themis mission is an attempt to settle a long-standing debate on the origins of the rippling lights.
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A main concern of this event is that the time identified as the substorm onset turns out to be about 50 minutes late. The other camp actually predicts reconnection to occur not at substorm onset but well after that. This is like someone who claims to be the first climber reaching the peak of Mt. Everest by ignoring the many people who have done it before him. Tony Lui
An aurora created during magnetic reconnection is a manifestation of energy transfer between solar wind and planetary magnetosphere. Particularly strong aurorae have been observed at the Jupiter’s and Saturn’s poles. It is possible that the energy exchange between a magnetosphere and the heliospheric current is far greater than previously believed. According to NASA Jupiter radiates twice as much energy as it directly receives from the Sun, this excess energy is possibly supplied by the heliospheric current. The exchange of energy modulates the Alfvén's current (which extends to the limits of the heliosphere with its return leg forming a closed circuit along the Sun’s surface) resulting in a possible feedback affecting solar surface activity. For more details including some numerical modeling see website: http://www.vukcevic.co.uk or (http://www.vukcevic.co.uk/solarcurrent.pdf)