Just to see if I can be called more names by Mr. Spires and R.L I thought it might be interesting to put up a couple of links that contain Descriptions and Photographs of some of the optical phenomenon caused by refracted light through sublimated ice crystals. BTW Sublimated ice crystals or Ice Fog as we know it in Alaska is a phenomenon unheard of until the advent of large scale Automobile polution in Arctic Environments. Early scientists could not have known about such phenomenon.

http://climate.gi.alaska.edu/Brian/sundog.html

http://www.gi.alaska.edu/ScienceForum/ASF0/036.html

http://www.sundog.clara.co.uk/atoptics/phenom.htm

Furthermore as added fuel to the fire I'd like to challenge anybody to look ahead of the many motion picture galleries of comets approaching the sun. Look well ahead of the comet, at least two to three times the length of the tail and watch the luminescence of the stars. Well ahead of the comet and to the sides you will see a definite change in the luminescence of the stars. If there isn't a very large dispersed cloud associated with the comet, why do the stars change in luminosity?

Interestingly, watching the stars through the tail, you seem to be able to see more of them than you do when the tail is not obstructing the view. I have no explanation of this phenomenon. Anybody care to guess?

Here is an example. Not the best one, but it is a start.

http://www.spacescience.com/headlines/y2000/ast05jul_1m.htm