That was a 22 degree lunar halo caused by high altitude ice crystals. The halo appears to cover 22 degrees of the sky because as the moonlight is refracted at a 21.85 degree angle by the hexagonal ice crystals.
(Probably more information than you wanted.) <img src="http://www.traveltalkonline.com/forums/images/graemlins/Grin.gif" alt="" />
Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. - Mark Twain
