The bright and vibrant waves of colors that cover the skies over northern Sweden form a rare natural phenomenon known as pearl clouds. Taken on January 12, when the Sun was just below the local horizon, this photo captures this impressive sight. These formations, which fall into the category of polar stratospheric clouds, are formed when ice crystals form in the normally cloudless lower stratosphere under the influence of extremely low temperatures. At an altitude of about 15 to 25 kilometers, these clouds offer a fascinating view by refracting the light of the Sun, even when it is not directly visible from the surface.

February 1, 2025 Astronomy Photo of the Day (NASA APOD)

Image Source & Copyright: Vojan Höfer