[OFF TOPIC] Anyone astronomical out there?

To anyone out there with any astronomy/meteorology expertise:  
I have a sky-watching question for you- last night the sky over Oxford,
UK,
was very lightly cloudy/overcast, whith brighter stars visible.  The
moon,
however, seemed completely clear, as was the sky in a perfect circle
round
it, perhaps 15-20 moon-diameters across.  The effect was fascinating and
beautiful, but what did it?  Obviously, the "clear patch" was also
cloudy,
but the moonlight was getting through it more directly.  Tyndall effect?
Ice crystals refracting the light?  Some sort of "moonbow"?  Will it be
back?

cheers,
Rob

"Rob Paul

Dept of Zoology
Oxford University
South Parks Road
Oxford
(01865) 271124
----------------------------------------------
"Once again, villainy is rotting meat 
before the maggots of justice!"
"