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From: ethan@utastro.UUCP (Ethan Vishniac)
Newsgroups: net.physics
Subject: northern lights (Aurora Borealis)
Message-ID: <200@utastro.UUCP>
Date: Fri, 27-Apr-84 17:45:47 EDT
Article-I.D.: utastro.200
Posted: Fri Apr 27 17:45:47 1984
Date-Received: Sun, 29-Apr-84 07:55:50 EDT
Organization: UTexas Astronomy Dept., Austin, Texas
Lines: 18

Fred (and any other interested people):
     A solar flare is an eruption in the upper layers of the sun's
atmosphere.  It involves a complicated, and not well understood, 
interaction between the charged particles ( mostly protons and
electrons, although some heavier ions are present) and the sun's
magnetic field.  The end result is that large numbers of the charged
particles are ejected from the sun at very large speeds.  When they
reach the Earth they can get trapped in our magnetic field.  The
interaction between these particles and our magnetic field produces
radiation (i.e. photons) which we call the northern lights.
   N.B. photons are massless, uncharged particles which are the
quanta of free electromagnetic radiation (light).

"Give a roar for Nora               Ethan Vishniac
 standing in the night              {ut-sally,kpno,ut-ngp}utastro!ethan
 Who saw the great Aurora           Astronomy Department
 Borealis burning bright"           University of Texas
    -Pogo                           Austin, Texas 78712