Why is there a shine around the moon at night?

[octelcogopod]

Silly question perhaps but I was thinking..
Shouldn't there in theory be a round light of the moon and then complete blackness around it?
Does the light reflect off small particles in the air or something?

 

[russ_watters]

Sometimes you will see it light around the moon just because of haze or moisture in the atmosphere (it isn't completely transparent), but then there are also halos at specific distances due to ice crystals in the atmosphere: http://en.wikipedia.org/wiki/Halo_(optical_phenomenon)