Thursday, September 13, 2007

Solar wind

The solar wind is a stream of charged particles which are expelled from the upper atmosphere of the sun. It consists mostly of high-energy electrons and protons that are able to get away the sun's gravity in part because of the high temperature of the corona and the high kinetic energy particles gain through a process that is not well understood at this time.

They are directly related to the solar wind, together with geomagnetic storms that can knock out power grids on Earth, auroras and the plasma tail of a comet always pointing away from the sun. While early models of the solar wind used primarily thermal energy to accelerate the material, by the 1960s it was clear that thermal hurrying alone cannot account for the high speed solar wind. Some additional acceleration mechanism is required, but is not presently known, but most likely relates to magnetic fields in the solar atmosphere. The solar wind is answerable for the overall shape of Earth's magnetosphere, and fluctuations in its speed, density, direction, and entrained magnetic field powerfully affect Earth's local space environment.

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