For the first time, astronomers have outlined and named the network of galaxies that includes the Milky Way, adding a line to our cosmic address and further defining our place in the universe. They call it Laniakea, which is Hawaiian for “immense heaven.”
Galaxies tend to gather in clusters, and those clusters move about in large networks called superclusters. But astronomers have struggled to figure out where one supercluster ends and another begins.
To trace the outline of the Milky Way’s supercluster, an international team of astronomers used high-powered telescopes to map the motions of neighboring galaxies relative to Earth. By figuring out which galaxies were being pulled toward us and which were being pulled away, the scientists could draw a circle (more or less) around the 100,000 galaxies that make up Laniakea.
The Milky Way rests on the outskirts of Laniakea, which measures 500 million light-years across and is 100 quadrillion times the mass of the sun.
The study’s lead author, R. Brent Tully, an astronomer at the University of Hawaii, said the new method for measuring the supercluster would be put to use measuring other large galactic networks.
“I think we’re going to use it on a whole bunch of scales, to see components within the Laniakea supercluster and the outline of adjacent supercluster systems,” he said. “We already have found a mini-supercluster adjacent to us.”
Dr. Tully’s team, which published its work in Nature, has not named the adjacent cluster.