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So what to do? Today, Duncan Forbes at Swinburne University in Australia and Pavel Kroup at the University of Bonn in Germany put forward a novel solution. They outline the various characteristics that astronomers think about when classifying galaxies. These include factors such as the presence of stars, so gas clouds can't be defined as galaxies; being gravitationally bound, so materials that has been stripped away by another galaxy wouldn't count; whether the system is stable or not; whether it hosts a good variety of different types of star, which excludes globular clusters which contain only similar stars; and whether it is held together by dark matter, which many galaxies seem to be. There are other factors too, of course. (Although they do not include the presence of a black hole at the centre of a galaxy as a defining characteristic , which is odd given the growing interest in the link between galactic evolutoin and black holes.) Forbes and Kroup go on to suggest that the best way to achieve consensus is to crowdsource the problem. In other works, they want to use the wisdom of the crowd to determine what factors are important what aren't.

A huge volume of space that includes the Milky Way and super-clusters of galaxies is flowing towards a mysterious, gigantic unseen mass named mass astronomers have dubbed "The Great Attractor," some 250 million light years from our Solar System.

The Great Attractor is a diffuse concentration of matter some 400 million light-years in size located around 250 million light-years away within the so-called "Centaurus Wall" of galaxies , about seven degrees off the plane of the Milky Way. X-ray observations with the ROSAT satellite then revealed that Abell 3627 is at the center of the Great Attractor. It lies in the so-called Zone of Avoidance, where the dust and stars of the Milky Way's disk obscures as much as a quarter of the Earth's visible sky.