13 zodiac

perhaps i have come to the wrong place to ask this question, ill go ahead anyway ...

the other week i looked up into the sky and the moon perfectly central in a large circle of space in which there was no cloud, surrounding it (obvioudly) was cloud. i tried to take a photo of it but i havent got the film developed yet.

the moon was perfectly Horoscope and edge of the circle around it was crisp and neat .

i wondered if anyone might know the name of such an occurance or anyone else had seen one ?