Today, here in Brazil, I have observed (and is still observing) an interesting phenomenon.
The Moon is near to a big star in the sky, but this is normal. The interesting part is what's around them.
A huge circle in which the moon and the star is inside. Why does this circle appear? What is it?
(This isn't a cloud. It looks like more something like a light reflection of a lamp.)
Unfortunately, I hadn't a good camera to catch this. I would appreciate having an image posted for this.