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.

2003 March 26
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A Lenticular Cloud Over Wyoming
Credit & Copyright: Mark Meyer (

Explanation: Is that a cloud or a flying saucer? Both, although it is surely not an alien spacecraft. Lenticular clouds can be shaped like a saucer, and can fly in the sense that, like most clouds, they are composed of small water droplets that float on air. Lenticular clouds are typically formed by high winds over rugged terrain and are particularly apparent when few other clouds are in the sky. Lenticular clouds can take on particularly strange, layered shapes. Above, a couple stopped their car near Yellowstone National Park in Wyoming, USA to photograph this lenticular cloud behind picturesque windmills.

Tomorrow's picture: light echoes

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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