Great Attractor

In Astronomy by Brian Koberlein3 Comments

There’s a region of space about 150 million light years away that is gravitationally attracting the galaxies in its region, including ours.  It is known as the great attractor, and we’re not entirely sure what’s there.  The problem is it happens to lie in the direction of the zone of avoidance, so our own galaxy is blocking our view.

When we measure the motion of our galaxy relative to other nearby galaxies, we find that the Milky Way is moving in the general direction of the great attractor at a speed of about 2.2 million kilometers per hour.  Observations of other galaxies also indicated motion in that direction, which gave rise to idea that a large concentration of galaxies must exist within that region.  But since the great attractor is within the zone of avoidance, it was difficult to determine what is there.

As I mentioned last time, the zone of avoidance is the region of sky where the plane of our galaxy is located.  Because of the gas and dust in the plane it is difficult to see beyond our galaxy in that direction.  But gas and dust obscure some wavelengths more than others.  Radio, infrared and x-rays, for example, can penetrate the region more readily, so with the rise of astronomy at these wavelengths (particularly x-rays) we began map the region of the great attractor.

A map of the great attractor and Shapley supercluster.  Credit: IfA

A map of the great attractor and Shapley supercluster. Credit: IfA

By the 1980s we were able to pin down the location of the great attractor, and found that it was centered at a large cluster of galaxies known as the Norma cluster.  Later observations found that this region doesn’t have enough mass to be the sole source of the attraction.  Instead a larger supercluster known as the Shapley supercluster.  It contains about 10,000 Milky Way sized galaxies, and is the largest known supercluster in the visible universe.  So now we have an understanding of the clusters pulling our galaxy.

Comments

  1. I believe that flat structures like galaxies connect by plasma filaments containing hot and cold superfluids. It’s the cosmic web, and our galaxy’s plane or dusty disk, and the ZOA extension outwards, and the Great Attractor, are aligned on this thin flat vast fermi like superfluid surface. we cannot see through this vast dusty ZOA, but they know our local galaxy group is part of the Virgo supercluster that also is such structurally oriented in this plane. I also believe that the Great attractor is very likely aligned with even larger cosmic structures, because it makes common reasonable sense to not constrain my mind with the size limits imposed upon from the big-bang. Thanks for allowing my cosmological beliefs to be posted that differ from mainstream dark matter cosmology.

  2. When you said when you measured the relative motion of our galaxy to, nearby galaxies, I think it makes more sense that it is relative to faraway galaxies and structures. Because all nearby galaxies to us should be equally attracted to the great attractor and therefore not much relative motion among the local groupings of galaxies

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