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Old 22-06-2008, 12:00 PM
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okiscopey (Mike)
Rocky Peak Observatory

okiscopey is offline
 
Join Date: Aug 2006
Location: Kandos NSW
Posts: 536
If the halo was colourless and 22 degrees in radius (approx. thumb-tip to little finger tip with hand held at arm's length) then it was probably an ice halo caused by refraction and reflection from tiny atmospheric ice crystals.

If coloured, then it was a 'corona' caused by diffraction or scattering by cloud water droplets.

I'm not an expert though! I got this from:

http://www.atoptics.co.uk/droplets/cormoon.htm

and

http://www.atoptics.co.uk/halo/circmoon.htm

Fascinating stuff!
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