Crepuscular rays are sunrays in twilight skies

Sunset view with dark rays cut into the orange glow and over a lake.
View at EarthSky Community Photos. | Juliana Karoway at Lake Quinsigamond, Shrewsbury, Massachusetts, captured this image on May 14, 2024. Juliana wrote: “Can you please tell me something about these clouds? I’ve never seen a sunset like this before!” Gladly, Juliana, and thanks for sharing! These are crepuscular rays, sunrays you can see in twilight skies thanks to small particles in the air. Read on to find out more about them.

What are crepuscular rays?

Crepuscular means resembling twilight or dim. This phenomenon occurs around sunrise or sunset, when the sun is below the horizon. And you can also see crepuscular rays when the sun is hiding behind clouds. They’re more noticeable when the sky is a bit darker and there is greater contrast between dark and light. We can see the rays of light thanks to dust, smoke or water droplets that scatter the light toward our eyes.

The darker streaks beside the sunrays are due to shadows, where the terrain or clouds block the sunlight from coming through. Sometimes those obstructions are below the horizon from your point of view, so it may not seem immediately clear what’s causing the darker rays.

When crepuscular rays extend from behind a cloud toward the ground, they also go by 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.

Parallel lines that seem to converge

Crepuscular rays appear to fan across the sky. But these sunrays are really parallel to each other. In fact, sometimes you can trace them all the way across the sky to the point on the horizon opposite the sunset. So, the next time you see them, remember to turn around. You might spot the fainter and less noticeable anticrepuscular rays. The illusion is similar to standing on train tracks and seeing how they appear to converge in the far distance in front of and behind you.

Left: orange sunrise, blue streaks coming out from a point on the horizon. Right: similar streaks in darker sky.
View at EarthSky Community Photos. | Ron Haggett in Yuma, Arizona, captured crepuscular rays (left) and anticrepuscular rays (right) on the morning of September 1, 2021. He wrote: “These photos were taken 9 minutes apart (6:00 and 6:09 a.m., local time). The image on the left is looking east before sunrise. Sunbeams can also extend across the sky and appear to converge at the antisolar point, the point on the celestial sphere opposite the sun’s direction. In this case, they’re called antisolar rays. The image on the right is at the antisolar point (due west).” Thank you, Ron!
Crepuscular rays: Arc of pink clouds and dark rays reaching from east to west horizon in long, flat picture.
View at EarthSky Community Photos. | Brendan Barnes captured crepuscular rays running all the way across the sky in this panoramic photo taken in Guam on October 28, 2020. He wrote: “I woke up this morning to bright pink clouds outside my window, so I ran upstairs to the roof and found crepuscular rays going the entire way from the rising sun toward the horizon to the west!” Thank you, Brendan!

Photo gallery of crepuscular rays

All of these photos were contributed by EarthSky friends. Thanks for sharing your awesome photos with us! Would you like to contribute? Submit your image here.

Clouds over water with 4 dark radial rays from horizon to zenith. All reflected in the water.
View at Earthsky Community Photos. | Guy Newlan in Orlando, Florida, captured this image on August 19, 2023. He wrote: “A cirrocumulus layer was an excellent screen for pre-sunrise crepuscular rays.” Thanks, Guy!
Lights of a small village at bottom, a distant mountain, and blue and pink radial streaks of light above.
View at EarthSky Community Photos. | Jenney Disimon captured these crepuscular rays in Sabah, North Borneo, Malaysia, on April 19, 2023. Jenney wrote: “On waking up, this was what I first saw. Crepuscular rays as the background of the iconic Mt. Kinabalu at dawn. And somewhere hidden was the old crescent moon. What an awesome sight!” Thank you!
Blue-grey sky with vast orange light rays coming from the bottom left. Two tiny dots white dots in the sky.
View at EarthSky Community Photos. | Helio C. Vital in Rio de Janeiro, Brazil, took this photo on March 1, 2023. Helio wrote: “The photo shows Jupiter and Venus only 35 arcminutes apart in the midst of bright crepuscular rays. Thank you!

Moon rays or moonbeams

Bright, small moon under clouds, reflected in a lake. Dark rays show across the moonlit clouds.
James Younger frequently camps at Vancouver Island and catches many wonderful sky sights from its shores. He captured these moon rays (in the clouds above) in August 2017.

Bottom line: Crepuscular rays are shadows in the sky of distant terrain or clouds. They form around twilight when particles in the atmosphere reflect the sun’s light beams toward our eyes. Sometimes you can see anticrepuscular rays on the horizon opposite the sun.

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May 18, 2024

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