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From: dipper@utastro.UUCP (Debbie Byrd)
Newsgroups: sci.astro
Subject: StarDate: October 27 The Amazing Sun
Message-ID: <1363@utastro.UUCP>
Date: Mon, 27-Oct-86 02:00:16 EST
Article-I.D.: utastro.1363
Posted: Mon Oct 27 02:00:16 1986
Date-Received: Mon, 27-Oct-86 22:21:00 EST
Organization: U. Texas, Astronomy, Austin, TX
Lines: 35

How the sun makes energy -- in a minute.

October 27  The Amazing Sun

The sun is a star because it shines, or produces its own energy.  And
the sun is able to shine because of thermonuclear fusion reactions
taking place deep in its interior.  Fission is where heavy atoms are
split to make energy.  Fusion is where light atoms fuse together under
conditions of high temperature and pressure -- like those at the center
of the sun.

With fusion, four atoms of the lightest and simplest element, hydrogen,
fuse to make a slightly different element, helium.  But one helium atom
is slightly less massive than the four hydrogen atoms which built the
helium atom.  This leftover mass is converted to energy which later
floods out from the sun in the familiar form of light and heat.

Energy flowing from the sun's core to its surface takes about 10
million years.  If the sun's energy production suddenly ceased, we
wouldn't know it until 10 million years from now.

The sun has been churning out energy for some four and a half billion
years.  Again, it feeds on itself -- in a process where matter is
converted into energy.  One ton of matter -- completely transformed --
would supply the energy needs of the entire human race for about a
year.  But the sun makes much more energy than that -- it consumes and
radiates away its mass at a rate of four million tons per second.

The sun has so much mass it could continue to do this for 100 billion
years -- but it won't.  It'll only use the hydrogen located near its
core -- and so will continue to shine as we know it for about another
five billion years.

Script by Deborah Byrd.
(c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin