Aurora Borealis By:  Jennifer Booth   The name Aurora Borealis is the latin name meaning "northern dawn."  Auroras occur when geomagnetic fieldlines guide electrons and protons from the magnetosphere or magnetosheath to earth's atmosphere.  Precipitating particles lose energy when they collide with neutral particles.  The particles ionized at about the same altitude as solar UV radiation when creating the ionosphere.  Some of the atmospheric constituents are at higher energy levels which causes auroral light to be emitted.   Most of the auroral particles have energy between 2 keV and 100 keV.  The energy levels are higher at night time.  Most ionization occurs at an altitude of 130 km.  Auroral emissions peak at about 100 km altitude.   Auroral studies can be devided into two categories:  Spectros copy and Morphology.  Spectroscopy is an instrument used to view visible electromagnetic radiation.  Morphology is the study dealing with the form and structures of organisms. If the intensity of auroral emissions is high enough, colors of the emission lines can be seen by the eye.  Typical colors are mostly green because of the automic oxygen line O1S (557.7 nm).     MARCH 19-24, 2001 AURORA GALLERY:  http://www.spaceweather.com/aurora/gallery_20mar01.html     The Northern Lights -- Aurora Borealis        http://www.uit.no/npt/nordlyset/nordlyset.en.html     Aurora Forecast for Wednesday, April 18, 2001             http://www.gi.alaska.edu/cgi-bin/predict.cgi     Jennifer Rae Booth