Dry heiligenschein (d-041217-183)
In gallery: Photos of the month (2004)
Related photos: Atmospheric optics
Light in water droplets
This photo was taken from an airplane while flying over the southwestern part of the USA (New Mexico). The bright spot to the lower left is called dry heiligenschein and marks the antisolar point (the point directly opposite the sun). The spot appears brighter than the surrounding areas because there are no shadows visible opposite the sun, since you look along the same direction as the light. The phenomenon is better visible on open but featureless structures, such as plains of sand or dust. An open structure causes the bright area to be better defined, because particles in an open structure block light from reaching underlying particles very effectively. If you look into the open structure in any direction away from the antisolar point, you see these integrated shadows and the region appears darker. Dry heiligenschein is also called the opposition effect, opposition light or gegenschein (when referring to the astronomical effect).
Photo taken on December 17 near the Arizona / New Mexico border (USA), using a Nikon D100 digital camera and 18-35mm f/4.5 Nikkor lens.