Moon Halo Over Somerville, MA on Flickr.
Another moon halo, almost a year from the last one I saw.
What is a moon halo?
From The Astronomy Photo Of The Day:
“This fairly common sight occurs when high thin clouds containing millions of tiny ice crystals cover much of the sky. Each ice crystal acts like a miniature lens. Because most of the crystals have a similar elongated hexagonal shape, light entering one crystal face and exiting through the opposing face refracts 22 degrees, which corresponds to the radius of the Moon Halo. A similar Sun Halo may be visible during the day.”
