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.

2023 February 9
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Nacreous Clouds over Lapland
Image Credit & Copyright: Dennis Lehtonen

Explanation: Vivid and lustrous, wafting iridescent waves of color filled this mountain and skyscape from KilpisjƤrvi, Finland. Known as nacreous clouds or mother-of-pearl clouds, they are rare. But their unforgettable appearance was captured looking south at 69 degrees north latitude at sunset on January 24. A type of polar stratospheric cloud, they form when unusually cold temperatures in the usually cloudless lower stratosphere form ice crystals. Still sunlit at altitudes of around 15 to 25 kilometers the clouds can diffract sunlight even after sunset and just before the dawn.

Tomorrow's picture: pixels in space


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