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.

2005 September 22
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Orange Moon, Red Flash
Credit & Copyright: Stefan Seip

Explanation: This remarkable telescopic image highlights the deep orange cast of a waning gibbous Moon seen very close to the eastern horizon earlier this week, on September 19. In fact, today's equinox at 22:23 UT marks the beginning of Fall in the Northern Hemisphere and makes this view from Stuttgart, Germany an almost Autumn Moon. While the long sight-line through the atmosphere filters and reddens the moonlight, it also bends different colors of light through slightly different angles, producing noticeable red (bottom) and green (top) lunar rims. Also captured here floating just below the Moon is a thin, red mirage (inset) -- in this case, an atmospherically magnified and distorted image of the red rim. Of course, this tantalizing lunar "red flash" is related to the more commonly seen green flash of the Sun.

Tomorrow's picture: a star is born

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