APOD: 2026 October 20 – An Anticrepuscular Rainbow Fan
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The post APOD: 2026 October 20 – An Anticrepuscular Rainbow Fan appeared first on NASA Science .
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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.
Explanation: This is an unusual rainbow. For one thing, the rainbow is not complete, appearing only in a sunlit fan — but that by itself is not very unusual. What is most unusual is the fake location of the Sun . The Sun appears to be toward the front, just below those hills — but it is not. That is not how rainbows work . Rainbows involve a backward reflection from falling rain , so that the Sun must really be behind you . In this case, gaps between clouds near the setting Sun allowed rays to cross the entire sky and appear to converge in front , an unusual phenomenon called anticrepuscular rays . The photo was taken with a phone last week at sunset in Presenzano , Italy . The seemingly reverse rainbow was noticed when hanging up laundry . Tomorrow’s picture: open space
Yesterday's Image APOD: 2026 October 19 – Treble Clef: Unusual X-ray Hot Radio Source Tomorrow's Image The post APOD: 2026 October 20 – An Anticrepuscular Rainbow Fan appeared first on NASA Science .