Nacreous Clouds over Sweden

Vivid and lustrous, wafting iridescent waves of color wash across this skyscape from northern Sweden. Known as nacreous clouds or mother-of-pearl clouds, they are rare. But their unforgettable appearance was captured in this snapshot on 2023 January 12 with the Sun just below the local horizon.

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 diffract the sunlight even when the Sun itself is hidden from direct view.

Marvel at these amazing space clouds and astronomical wonders, which provide stunning displays in our celestial night sky and contribute to the beauty of the cosmos. Delicate cosmic dust plays a part in forming such spectacle.