Tag Archives: blue moons and suns in Britain

When the sun turns blue

One of the effects of volcanic ash in the atmosphere is to scatter light.  When only longer light waves reach the earth, the blood-red sunsets associated with volcanic explosions are observed.

More unusually, if the particles suspended in the atmosphere are all of a particular size, rather than a mixture, the sun and moon can turn blue.  This phenomenon was seen in Britain when Krakatoa erupted in 1883:

Clouds of dust hung suspended in the stratosphere for months, causing strange after-effects.  All over the world, the most beautiful sunsets were witnessed.  In Paris, New York, London, and Cairo, the setting sun appeared blue, leaden, green and copper-coloured.  At night, the moon and stars appeared green. –  August 1963 issue of Popular Science