CfA2 Great Wall

The Great Wall includes clusters Hercules, Coma and Leo on the right of this view of the local universe.

The Great Wall (also called Coma Wall), sometimes specifically referred to as the CfA2 Great Wall, is an immense galaxy filament. It is one of the largest known superstructures in the observable universe.

This structure was discovered c. 1989 by a team of American astronomers led by Margaret J. Geller and John Huchra while analyzing data gathered by the second CfA Redshift Survey of the Harvard-Smithsonian Center for Astrophysics (CfA).


The CfA2 Great Wall is a galaxy wall, one of the three subtypes of galaxy filaments, the other two being galaxy sheets and supercluster complexes. The term "Great" has been added to distinguish it as an even larger type compared to standard galaxy walls. Great walls are so rare that only five and possibly six (if the disputed Hercules-Corona Borealis Great Wall is counted) of them have been discovered to date.

The CfA2 Great Wall has the maximum dimensions of either 500 million or 750 million light years; depending upon the figure and the reference used. It is 200 million light years in width and about 16 million light years in thickness. Its nearest point is about 300 million light years from Earth, while its farthest point is 550 million light years away. It consists of three massive galaxy superclusters: Hercules, Coma and Leo.

The CfA2 Great Wall includes Coma Filament.

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