III. The Celestial Globe 

B. Using the celestial globe

The earth moves in two ways.  It revolves around the sun, and it
rotates on it's axis.  The celestial globe simulates these motions so
that you can calculate what the sky looks like at a certain day and
time.  Using the celestial globe is a three step process.

  1. Moving the globe so that the top of the globe corresponds to the
     top of the sky.
  2. Moving the sun to take into account the earth's movement around it.
  3. Moving the globe to take into account the earth's rotation along it's
     axis.

Step 1. Locating up.......

When you look up, what you are really doing is looking "out" from the
earth.  Because the earth is round, a person looking up from the north
pole is looking at a different direction than a person looking up from
Austin, Texas or from a person looking up from Australia.

The first step in using the celestial globe is to arrange things so
that "up" on the globe is "up" in real life.  You do this by
positioning the globe so that Texas on the globe in the center is
facing up.  Once you have done this, you will not need to worry about
the globe in the center anymore.

Step 2. Taking account of the earth's motion around the sun........

The earth moves around the sun once a year.  As the earth moves around
the sun, the sun's location in the sky seems to change in such a way
that in makes one complete journey every year.  If you look at the
globe, you will see dates marked on a line that stretches around the
globe.  These date mark where is sun is on a particular date.  If you
want to see what the sky looks like in