MOON HALO ALERT:

MOON HALO ALERT: It's cold outside. The Moon is waxing full. There's ice in the air. Add them all together and you have perfect conditions for a ring around the Moon:

Photo details: Canon EOS 5D, 8mm fisheye lens, ISO 200, 10s

"I happened to take a stroll outside last night," says photographer David Harvey of Tucson, Arizona. "The Moon was nearly overhead and surrounded by this eye-catching 22^o halo."
Such haloes are formed when moonlight passes through pencil-shaped ice crystals floating in high freezing clouds. When you see a 22^o moon halo, be alert for moondogs and moon pillars, too. They are formed by plate-shaped ice crystals that often accompany their pencil-shaped cousins.
The Moon is full on Dec. 31st. Mark your calendar for haloes.
more images: from James Helmericks on the Colville River Delta in northern Alaska; from John C McConnell of Maghaberry Northern Ireland; from Jens Hackmann of Bad Mergentheim, Germany; from Gerhard Dangl of Nonndorf, Austria;


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