Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2025 February 4
A rainbow is pictured over the sea between an island
and land. A series of
light rays appears to connect the horizon to the rainbow.
Please see the explanation for more detailed information.

Anticrepuscular Rays: A Rainbow Fan over Spain
Image Credit & Copyright: Julene Eiguren

Explanation: Yes, but can your rainbow do this? Late in the day, the Sun set as usual toward the west. However, on this day, the more interesting display was 180 degrees around -- toward the east. There, not only was a rainbow visible, but an impressive display of anticrepuscular rays from the rainbow's centre. In the featured image from Lekeitio in northern Spain, the Sun is behind the camera. The rainbow resulted from sunlight reflecting back from falling rain. Anticrepuscular rays result from sunlight, blocked by some clouds, going all the way around the sky, overhead, and appearing to converge on the opposite horizon -- an optical illusion. Rainbows by themselves can be exciting to see, and anticrepuscular rays a rare treat, but capturing them both together is even more unusual -- and can look both serene and surreal.

Jigsaw Challenge: Astronomy Puzzle of the Day
Tomorrow's picture: comet set


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