Clustered about Clusters

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Clustered about Clusters
« on: 23/06/2009 08:33:34 »
Just an enquiry into the behaviours if galaxies within a cluster. As it is known(as far as we can safely say) that galaxies are all receding from each other. Are the galaxies within each cluster also moving away from each other? or is there a directionality of each galaxy within the cluster, of the cluster.


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Clustered about Clusters
« Reply #1 on: 02/07/2009 09:39:38 »
Galaxies in clusters are attracted to each other and not expanding significantly.  It is only on the very largest scales of gaps between the clusters of galaxies that the expansion dominates gravitational attraction  they move in sort of unstable orbits around each other altough there is a strong tendency for them to collide and clump together in the large galaxies that usually lie at the heart of the cluster.
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Clustered about Clusters
« Reply #2 on: 02/07/2009 11:57:06 »
Despite the expansion of the Universe, we still ge pulled down to Earth all the time. Galaxies are in the same situation. It's all a matter of how much the local gravitational potential is, compared with how fast things are traveling. The Big gaps will be getting bigger but the Small gaps will be getting smaller. The net density is getting less, though.