* Ice Crystals: Halos are optical illusions created by the interaction of moonlight with ice crystals in high-altitude clouds called cirrostratus clouds. These clouds are thin and wispy, and the ice crystals act like tiny prisms, refracting the moonlight.
* Refraction and Dispersion: When the light passes through these crystals, it's bent (refracted), and different colors are separated (dispersed), just like a rainbow. This is why halos often have a faint, iridescent appearance.
* Angle of Light: The specific shape of the halo (a circle, a ring, or even arcs) depends on the angle at which the light hits the ice crystals.
So, there's no actual circle around the moon, it's an optical effect created by ice crystals in the atmosphere!
