Astronomy Picture of the Day

Discover the cosmos! Each day we feature a different image or photograph of our fascinating universe, along with a brief explanation written by a professional astronomer.

January 14, 1996
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A Distant Cluster of Galaxies
Credit: NASA, HST, A. Dressler (CIW)

Explanation: Every bright object in this 1994 photograph by the Hubble Space Telescope is a galaxy. Oddly - most of the objects 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 Dawn of the Clusters

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Authors & editors: Robert Nemiroff (GMU) & Jerry Bonnell (USRA).
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