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.

December 7, 1997
See Explanation.  Clicking on the picture will download 
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A Distant Cluster of Galaxies
Credit: A. Dressler (CIW), NASA

Explanation: In this 1994 Hubble Space Telescope photograph, every bright object is a galaxy. Oddly - most of them are spiral galaxies. This rich cluster of galaxies, named CL 0939+4713, is almost half way across the visible universe. Photos like this indicate that clusters in the past contained a higher fraction of spirals than do nearby clusters which are usually dominated by elliptical galaxies.

Tomorrow's picture: The Trifid Nebula in Red, White and Blue

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.