In an area of the sky obscured from us by the Milky Way Galaxy there lies a gravity anomaly called “The Great Attractor”.  Noticed first in 1973, and again in 1978, by variations in the expected expansion of the universe.  Something was pulling galaxies toward it; in fact, it was believed to be pulling the Milky Way and Andromeda toward it.

The Great Attractor, as it has been called, is not a galaxy.  It’s not a cluster of galaxies.  It’s believed to be a “supercluster” of galaxies.

NASA/JPL IPAC/CalTech, by Thomas Jarrett

Looking at this chart, you can see the Great Attractor slightly below the plane of the Milky Way (follow the blue arrow).  Now, look above it.  Do you see something called the Shapley Concentration (yellow arrow)?  It’s behind the Great Attractor, and much further out.  It’s also what we’re being drawn toward.

I hear gasps of dismay.  In 2005, X-ray surveys in the “Zone of Avoidance” (the area behind the Milky Way which we normally can’t study very well) confirmed that it was the Shapley Concentration we were being pulled toward, not the Great Attractor.  In all fairness, it was the Great Attractor and its gravity anomaly which caused scientists to study the area so closely, only to rediscover this huge concentration behind it.

Richard Powell Atlas of the Universe, all rights reserved.

The Shapley Concentration is a massive overdensity in the constellation of Centaurus.  It is the largest concentration of matter in the observable universe.  Astronomers have long known the Milky Way is moving toward the constellation Centaurus, and at quite a respectable 1.4 million miles per hour.  Many thought the pull was the Great Attractor, but with the use of X-rays to peer beyond the Milky Way’s dust, they learned the Great Attractor didn’t have nearly the matter they had originally thought.  They also got a good look at the Shapley Concentration, and saw that it did have the matter.  As a matter of fact, the Great Attractor is being pulled toward the Shapley Concentration.

Containing many thousands of times the mass of the Milky Way, and about 650 Mly away (that’s million light years), the Shapley Concentration is a rare supermassive cluster of many galaxies.  We are being drawn inexorably toward it, and will one day become a part of the cluster ourselves.

Oh, not “us” as in you and me… I mean “us” as in this galaxy.  Humanity will be long gone by then, extinct on a planet no longer able to support life as we know it.  In fact, we’ll probably run into Andromeda long before we become a bug on the windshield of the Shapley Concentration.

So to speak.

Click here to see a larger view of the first image.  It’s really cool.