Laniakea: Your Cosmic Address

When you give your address to somebody, you want to make sure you can be found. In case you’re going to do that with an alien civilisation, you’d better be as precise as possible. So, this is the cosmic address you may want to use: Earth, Solar System, Milky Way, Local Group, Virgo Supercluster, Laniakea.

This work, published in Nature by a team of astronomers at the University of Hawaii at Manoa, sheds light on the large-scale structure of the Universe, which is the result of a conflict between two forces. You have gravity, which pulls things, including galaxies, together, and the overall expansion of the cosmos, which pushes them apart, creating superclusters on one side and huge dark voids on the other. There are four huge areas identified so far: Laniakea, its neighbouring Perseus-Pisces supercluster, and two other superclusters, Shapley and Coma, on the far side of the universe.

Until now, Virgo Supercluster would have been enough. But now, scientists have discovered that even this supercluster is part of a much larger agglomerate of galaxies – stretching across a diameter 520m light years, including the Great Attractor, a sort of gravitational valley where the galaxies seem to converge. This super-supercluster has been named Laniakea, or “immeasurable heaven” in Hawaiian, by the team that discovered it, and it contains 100,000 large galaxies that, together, have the mass of 100 million billion suns. Our home galaxy, the Milky Way, just lies on the far outskirts of Laniakea.

Photo Credit: Nature