Feel Your Halo

In a winter mountain night of Nagano prefecture in Japan, stars of Taurus (upper right), Orion (middle right), and Canis Major (lower right) surrounds a beautiful lunar halo. Note the red planet Mars on the lower left of the Moon. Large halo around the Moon or the sun 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 Sun or the Moon Halo.