12-11-2007, 02:54 PM
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NASA Spacecraft Make New Discoveries about Northern Lights
http://science.nasa.gov/headlines/y2...htm?list762767
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Scientists have been tracking and studying substorms for more than a century, yet these phenomena remained mostly unknown until THEMIS went into action.
Even more impressive was the substorm's power. Angelopoulos estimates the total energy of the two-hour event at five hundred thousand billion (5 x 1014) Joules. That's approximately equivalent to the energy of a magnitude 5.5 earthquake.
Where does all that energy come from? THEMIS may have found an answer:
"The satellites have found evidence for magnetic ropes connecting Earth's upper atmosphere directly to the Sun," says Dave Sibeck, project scientist for the mission at the Goddard Space Flight Center. "We believe that solar wind particles flow in along these ropes, providing energy for geomagnetic storms and auroras."
A "magnetic rope" is a twisted bundle of magnetic fields organized much like the twisted hemp of a mariner's rope. Spacecraft have detected hints of these ropes before, but a single spacecraft is insufficient to map their 3D structure. THEMIS's five satellites were able to perform the feat.
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http://science.nasa.gov/headlines/y2000/ast04oct_1.htm
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Magnetospheres around the Solar System
Most planets are huge magnets with magnetic fields that extend far into space. The exceptions are Venus, Mars, and probably Pluto (although we have not yet visited Pluto and don't know for sure). When the solar wind runs into a planetary magnetic field, the electrons and ions are deflected around it. The cavity that the planetary magnet carves out is called a magnetosphere. It's shaped something like a comet with a long tail that points away from the Sun.
Earth's Magnetosphere
Jupiter's magnetosphere is the biggest thing in the entire solar system. Not only is it large enough to hold all of Jupiter's moons, but the Sun itself could fit inside many times over. If you could see Jupiter's magnetosphere at night, it would appear to be nearly twice as wide as the Full Moon.
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