I have a sun include file defined thusly:

#ifndef (sun_radius_m)
#declare sun_radius_m = 6.96e8;
#end

#ifndef (sun_distance_m)
#declare sun_distance_m = 1.5e11;
#end

#ifndef (sun_render_distance_m)
#declare sun_render_distance_m = sun_distance_m;
#end

#declare sun_render_radius_m = sun_render_distance_m * sun_radius_m /
sun_distance_m;

#declare sun_color = rgb< 1, 1, .5 >;

#declare sun_sphere =
sphere
{
  <0,0,0>, sun_render_radius_m
  pigment { color sun_color }
  finish { ambient 1 }
}

#declare sun =
light_source
{
  < 0, sun_render_distance_m, 0 >
  color sun_color
  looks_like { sun_sphere }
}

I wanted to use this to easily create a sun light source for outdoor scenes.
If I declare
a sun object at the default render distance with a camera say at the origin
and then rotate
the sun into the camera's view ( I have to reduce the angle quite a bit ),
things in the scene
will be illuminated but the sun itself will not be visible.  If I make the
render distance around
10000000 or less, the sun is visible.  Can someone explain this to me?

Also, does anyone have any examples of how to create a photo-realistic
atmosphere like the
ones from terragen in POV?  Specifically how to make the atmosphere scatter
blue and thus make
the sun redder as it has to shine through more atmospheric media.  Also the
creation of sun rays
through clouds.

Any help is much appreciated...

J.D.

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