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.

2019 July 26
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The Veins of Heaven
Image Credit & Copyright: P-M Hedén (Clear Skies, TWAN)

Explanation: Transfusing sunlight through a still dark sky, this exceptional display of noctilucent clouds was captured earlier this month, reflected in the calm waters of Vallentuna Lake near Stockholm, Sweden. From the edge of space, about 80 kilometres above Earth's surface, the icy clouds themselves still reflect sunlight even though the Sun is below the horizon as seen from the ground. Usually spotted at high latitudes in summer months the night shining clouds have made a strong showing so far during the short northern summer nights. Also known as polar mesopheric clouds they are understood to form as water vapour driven into the cold upper atmosphere condenses on the fine dust particles supplied by disintegrating meteors or volcanic ash. NASA's AIM mission provides daily projections of noctilucent clouds as seen from space.

Tomorrow's picture: launch and last light


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