Milky Way’s neighborhood may be 100 times larger than previously believed

Nature : The Milky Way is just one of thousands of galaxies arranged in a group known as the Virgo Supercluster. Now, Brent Tully of the University of Hawaii and his colleagues argue that the Virgo Supercluster is just one part of an even larger supercluster that they named Laniakea—Hawaiian for “immeasurable heaven.” Tully’s team members mapped and predicted the motions of 8000 of the nearest known galaxies, which revealed boundaries that they used to define the edges of the new supercluster. Laniakea is 520 million light-years across and has the mass of 100 billion Suns, which makes it 100 times larger than the Virgo Supercluster in both volume and mass. The use of galaxy motion, instead of static images, helps better define the cosmic structures because it shows the gravitational relationships between both the visible matter of galaxies and the dark matter that permeates the universe.