The Milky Way's 'City' Just Got a New Name

Astronomers sometimes think of galaxies as being like massive neighborhoods, using gravity to bind stars, dust, and dark matter. As neighborhoods, they don't sprawl. Rather, they're found within groups of dozens of other galaxies, and those groups within massive "superclusters" that contain hundreds of galaxies, all interconnected by a network of thread-like baryonic matter. 

Now, our own galactic megalopolis has a name: "Laniakea," meaning "immense heaven" in Hawaiian. An international team of astronomers, led by renowned scientist R. Brent Tully, has defined the supercluster of galaxies containing the Milky Way, publishing their work today in Nature. 

The astronomers studied how the movement of our local galactic group is affected by the gravitational pull of other galaxies within Laniakea, and used the data to create a sort of imaginary map of the supercluster. 

Above is part of that map. It shows a slice of Laniakea, shown within the "supergalactic equatorial plane"—an imaginary plane that shows not only our supercluster but also others nearby. The white lines show how Laniakea's gravity pulls galaxy groups towards it, while dark blue flow lines are away from Laniakea's attraction. The orange circle encloses the outer limits of these gravitional flows, effectively charting the perimeter of our supercluster. Their findings state this region contains the mass of about 1017 suns: 100 million billion suns.

For finer clarity, have a look at this strangely moving video, which was produced to accompany the paper.