A new cosmic map is giving scientists an unprecedented look at the boundaries for the giant supercluster that is home to Earth’s own Milky Way galaxy and many others. Scientists even have a name for the colossal galactic group: Laniakea, Hawaiian for “immeasurable heaven.”
Image 1: Scientists have created the first map of a colossal supercluster of galaxies known as Laniakea, the home of Earth’s Milky Way galaxy and many other. This computer simulation, a still from a Nature journal video, depicts the giant supercluster, with the Milky Way’s location shown as a red dot. Credit: [Nature Video](https://www.youtube.com/watch?v=rENyyRwxpHo)
Image 2: This computer-generated depiction of the Laniakea Supercluster of galaxies, which includes the Milky Way galaxy containing Earth’s solar system, shows a view of the supercluster as seen from the supergalactic equatorial plane. Credit: SDvision interactive visualization software by DP at CEA/Saclay, France
The scientists responsible for the new 3D map suggest that the newfound Laniakea supercluster of galaxies may even be part of a still-larger structure they have not fully defined yet.
"We live in something called ‘the cosmic web,’ where galaxies are connected in tendrils separated by giant voids," said lead study author Brent Tully, an astronomer at the University of Hawaii at Honolulu.
Galactic structures in space
Galaxies are not spread randomly throughout the universe. Instead, they clump in groups, such as the one Earth is in, the Local Group, which contains dozens of galaxies. In turn, these groups are part of massive clusters made up of hundreds of galaxies, all interconnected in a web of filaments in which galaxies are strung like pearls. The colossal structures known as superclusters form at the intersections of filaments.
The giant structures making up the universe often have unclear boundaries. To better define these structures, astronomers examined Cosmicflows-2, the largest-ever catalog of the motions of galaxies, reasoning that each galaxy belongs to the structure whose gravity is making it flow toward.
"We have a new way of defining large-scale structures from the velocities of galaxies rather than just looking at their distribution in the sky," Tully said.