Twilight Rays

March 18, 2002


Provided by: Adolf Riess
Summary authors & editors: Adolf Riess; Jim Foster

This beautiful image of anticrepuscular (subsolar rays) rays was taken about 1/2 hour before sunset. As the Sun sets or rises, rays of light (crepuscular or twilight rays) interspersed with darker bands (shadows) can sometimes be seen in the direction of the Sun. The shadows are most often caused by clouds below the horizon but can also be caused by mountain peaks blocking the Sun. On occasion, these rays can extend all the way across the sky and can be seen opposite the Sun as anticrepuscular rays. Both crepuscular and anticrepuscular rays converge toward the horizon. It's a matter of perspective, similar to standing on a railroad track and looking at the rails in the distance.

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