Moon Halo


Like sun halos, moon halos can be seen when the weather is cold with thin, high clouds. They are caused by refraction off of ice crystals high in the atmosphere, and form a ring 22 degrees in radius. This pre-dawn halo was seen when the gibbous moon was in the constellation Taurus. Inside the bow, at the "5 o'clock" position, is the bright star Aldebaran; Betelgeuse (in Orion) is right on the bow at 7 o'clock, and Capella (in Auriga) is straight up at 12 o'clock. Outside the bow to the lower right is the bright planet Mars.

Date: October 21, 2005
Time: 5:24 a.m. MST
Location: Phoenix, Arizona
Camera: Olympus OM-1 35mm SLR on fixed tripod
Film: Fuji Provia 100 slide
Focal length: 24 mm
Aperture: f/2.8
Exposure time: 1 minute
Scanner: Nikon Coolscan LS-2000 (boosted contrast and saturation slightly to make bow more visible)

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Revised: December 14, 2006
Copyright © 2005 Joe Orman
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