Crepuscular means like twilight or dim. This phenomenon occurs around sunrise or sunset, when the sky is somewhat dark. Crepuscular rays may appear to fan across the sky, but the rays are really parallel to each other. The sunbeams appear to diverge, much as a road that looks narrow in the distance appears wide beneath your feet. Airborne dust, droplets of water and the air molecules themselves are what make the sunrays visible. Next time you see them, remember to turn around. You might be in luck and see fainter and less noticeable anticrepuscular rays.
Crepuscular rays can also go by the name of sunray. Some people also apply the term crepuscular ray for sunbeams that radiate from the direction of the sun while it is still above the horizon but hidden behind clouds. Although technically, a crepuscular ray requires the sun to be below the horizon. The photos of sunbeams coming from a sun still above the horizon also have the nickname Jacob’s Ladder. The term comes from a story in the bible where Jacob has a dream in which he sees a ladder leading up to the golden light of heaven with angels ascending and descending.
All of these photos were contributed by EarthSky friends. Thanks for sharing your awesome photos with us!
Photo gallery of crepuscular rays
Moon rays or Moonbeams
Bottom line: Crepuscular rays form when the sun is below the horizon but light beams streak into the darkening sky. Anticrepuscular rays are on the horizon opposite the sun.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. She and her husband live in Tennessee, where they enjoy guitar playing and singing. They have 2 grown sons.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. In 2020, she was the Education Prize from the American Astronomical Society, the largest organization of professional astronomers in North America. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.
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