TL;DR
NASA’s Astronomy Picture of the Day for Oct. 20, 2026, features a fan-shaped rainbow photographed at sunset in Presenzano, Italy. NASA explains that the Sun only appears to be in front of the photographer: anticrepuscular rays from gaps in clouds near the setting Sun crossed the sky and seemed to converge in the opposite direction.
NASA’s Astronomy Picture of the Day for Oct. 20, 2026, features a fan-shaped rainbow photographed at sunset in Presenzano, Italy, that appears to form opposite the Sun. The agency’s explanation says the apparent reversal is an optical effect: rays passing through gaps in clouds near the setting Sun crossed the sky and appeared to converge in front of the photographer.
The picture, credited to Aurelia Degli Esposti, shows only part of a rainbow within a sunlit fan. NASA notes that a rainbow does not need to appear as a complete arc, so the incomplete shape is not the image’s most unusual feature. The striking detail is the apparent location of the Sun, which seems to be just below hills in front of the camera.
That apparent position conflicts with the usual geometry of a rainbow. NASA’s explanation says rainbows involve light reflected backward by falling rain, meaning the Sun must be behind the viewer. In this photograph, the setting Sun was not in front of the photographer as the scene might suggest. Instead, the gaps between clouds let rays travel across the sky and appear to converge in the opposite direction.
NASA identifies those apparent rays as anticrepuscular rays. The photograph was taken with a phone at sunset the week before publication. According to the APOD caption, the photographer noticed the effect while hanging up laundry.
Why the Rainbow Seems Reversed
The image offers a clear example of how perspective can make light appear to come from an unexpected direction. The apparent convergence of the rays in front of the viewer does not mean the Sun has moved or that the rainbow forms through a different process. It reflects the way distant light paths appear to meet when viewed across the sky.
That distinction helps explain why the scene can look inconsistent with the familiar rule that the Sun must be behind someone viewing a rainbow. NASA’s account links the fan of light to the setting Sun behind the photographer and to cloud gaps that allowed rays to cross the sky. The rainbow remains partial, while the unusual perspective supplies the image’s central visual puzzle.
For readers, the APOD pairs a specific photograph with a short explanation of the geometry behind it. It also shows how an everyday observation—in this case, noticing light while doing laundry—can reveal a less familiar atmospheric effect. The image is an astronomy feature, not a report of a new discovery or a change in scientific understanding.
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How the APOD Describes the Scene
NASA’s Astronomy Picture of the Day publishes an image or photograph with a brief explanation. The Oct. 20 entry is credited to the photographer, Aurelia Degli Esposti, and its explanation is attributed to the APOD editorial team: Robert Nemiroff, Jerry Bonnell, Cecilia Chirenti and Keighley Rockcliffe. NASA lists the service as involving its Astrophysics Science Division at Goddard Space Flight Center, NASA Science Activation and Michigan Technological University.
The caption distinguishes between two features that might otherwise be confused. A rainbow appearing only in part of a sunlit area is not, by itself, unusual, NASA says. The less familiar feature is the apparent reversal of the Sun’s position. The explanation attributes that appearance to anticrepuscular rays associated with gaps in clouds near sunset, rather than to a rainbow forming in front of the Sun.
The photo was taken in Presenzano, Italy, during the week before the APOD appeared. NASA does not give an exact capture date or additional measurements for the scene in the supplied caption. The publication is dated Oct. 20, 2026, and lists the following day’s picture as “open space.”
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What the Caption Does Not Specify
The APOD caption does not provide the photograph’s exact date and time, the phone model, weather measurements or the photographer’s account beyond saying the effect was noticed while hanging laundry. It also does not give technical details such as the viewing direction or the position of the clouds. Those details cannot be established from the supplied text.
NASA presents anticrepuscular rays as the explanation for the apparent convergence, but the caption does not report a separate investigation or measurements of the scene. The publication is a concise image explanation, not a study announcing new findings. The source material also does not specify the rainbow’s distance, duration or the precise arrangement of raindrops that produced the visible arc.
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The Next APOD Image
NASA’s listing says the next Astronomy Picture of the Day, scheduled for Oct. 21, 2026, is titled “open space.” The provided source does not include further details about that image or say whether NASA plans additional reporting on the rainbow photograph. The Oct. 20 entry stands as a single-day image feature explaining the scene’s apparent reversal.
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Key Questions
Where was the rainbow photograph taken?
The APOD caption says it was taken at sunset in Presenzano, Italy, using a phone.
Why does the Sun seem to be in front of the photographer?
NASA says the Sun only appears to be in front. Rays from gaps in clouds near the setting Sun crossed the sky and seemed to converge in that direction.
What are anticrepuscular rays?
In NASA’s explanation, they are rays associated with gaps in clouds near the setting Sun that appear to cross the sky and converge opposite the Sun.
Does a rainbow have to appear as a complete arc?
No. NASA says this rainbow appears only within a sunlit fan, and that an incomplete rainbow is not especially unusual.
When was the picture published?
NASA published it as the October 20, 2026, Astronomy Picture of the Day. The caption says the photograph was taken the week before.
Source: primary
