In astronomy news this week, another big mystery has (possibly) been solved, and unfortunately it is a rather mundane solution. 

In the early 1970s, astronomers who were studying distant galaxies noticed that they were being pulled towards a mysterious region near the Hydra-Centaurus supercluster, approximately 200 million lightyears away from us. Assuming that gravity had the same properties on cosmic scales as it does within our own galaxy, this region appeared to contain a concentrated mass equal to tens of thousands of Milky Way galaxies. Unfortunately for astronomers of that era, the source of this gravitational pull was on the opposite side of the galactic core, which is filled with so many stars and other objects that it completely obscures our vision of the other side. Whatever was pulling on the galaxies was hiding from us.

This mysterious region became known as the Great Attractor, and over the next four and a half decades was the subject of extensive study and research. Its location and mass were more accurately determined, but the exact cause of the gravitational forces was still a mystery.

However last week new results were released which used the Parkes Radio Telescope to at least partially solve the mystery. While the center of the galaxy blocks out visible light, it is not as opaque to lower frequency radio waves. By collecting radio waves that had passed through the galactic core, astronomers were able to generate images of the other side, and discovered 883 galaxies, with approximately one third of these being previously undetected in any form. 

This would seem to confirm that at least part of the Great Attractor is nothing more than a particularly dense clump of massive galaxies. Our planet and the Milky Way just happen to be aligned such that the biggest cluster of large galaxies is directly opposite and previously not visible to us. 

Of course a lot more research will still be required. We still do not know if these galaxies are massive enough to account for the entire effect, or if they are just part of it. Or if they are the cause of the effect, or a result of older galaxies being pulled by the same mysterious forces.

Either way it is a big step towards solving the puzzle, even if the results are less exciting than some had hoped for.