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.

2011 August 24
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A Pileus Iridescent Cloud Over Ethiopia
Image Credit & Copyright: Esther Havens (Light the World)

Explanation: Yes, but how many dark clouds have a multicoloured lining? Pictured, behind this darker cloud, is a pileus iridescent cloud, a group of water droplets that have a uniformly similar size and so together diffract different colours of sunlight by different amounts. The above image was taken just after the picturesque sight was noticed by chance by a photographer in Ethiopia. A more detailed picture of the same cloud shows not only many colours, but unusual dark and wavy bands whose origins are thought related to wave disturbances in the cloud.

Tomorrow's picture: avoid the ghosts


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