Re: [OFF TOPIC] Anyone astronomical out there?

Rob Paul wrote:
> 
> 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?

	I'm not sure, but I've seen the effect before.	I believe it
	is, as you mentioned, due to ice crystals in high altitude
	cirrus clouds.