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GlennA said:
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="" />

This weather phenomenon is the same thing that causes "sun dogs" or in extreme cases "sun halos" to appear. I recall having to calculate that angle as part of an undergraduate optics (physics) exam <img src="http://www.traveltalkonline.com/forums/images/graemlins/Thumbsup.gif" alt="" />

... DIF all the time...
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