If you wanted to send a letter to Earth from the other side of the universe, “Milky Way” wouldn’t be a complete address. Our galaxy is one of about 100,000 galaxies that belong to a single giant structure roughly 500 million light-years across. Its name is Laniakea, Hawaiian for “immeasurable heaven,” and astronomers only drew its borders in 2014.
Here’s what the Laniakea Supercluster is, how scientists mapped something that size, and why everything inside it, including us, is drifting toward a mysterious region called the Great Attractor.
Laniakea Supercluster: Key Facts
| Name meaning | “Immeasurable heaven” in Hawaiian (lani = heaven, ākea = spacious, immeasurable) |
|---|---|
| Size | About 500 million light-years across |
| Galaxies | Roughly 100,000 |
| Mass | About 100 quadrillion (1017) times the mass of the Sun |
| Defined | 2014, by R. Brent Tully, Hélène Courtois, Yehuda Hoffman and Daniel Pomarède |
| Mapped from | The motions of more than 8,000 galaxies |
| Center of flow | The Great Attractor |
| Milky Way’s position | Near the outer edge |
Our Full Cosmic Address
Starting at home and zooming out, our complete address in the universe looks like this:
- Earth, the third planet from the Sun
- The Solar System, the Sun and everything orbiting it
- The Orion Arm, a minor spiral arm of our galaxy
- The Milky Way, a spiral galaxy of 100–400 billion stars
- The Local Group, about 80 galaxies including Andromeda and Triangulum
- The Virgo Supercluster, a region of galaxy groups centered on the Virgo Cluster
- The Laniakea Supercluster, our true home at the largest scale we can define
Each step is enormously bigger than the last. The Milky Way is about 100,000 light-years wide. Laniakea is around 5,000 times wider.
From the Local Group to the Virgo Supercluster
Our first neighbors are the galaxies of the Local Group. The biggest is Andromeda, about 2.5 million light-years away. The Local Group spans roughly 10 million light-years and is held together by gravity.
Zoom out further and the Local Group turns out to be a small part of the Virgo Supercluster, a flattened collection of galaxy groups and clusters. At its heart is the Virgo Cluster, a dense swarm of more than 1,000 galaxies about 54 million light-years from us.
For decades, the Virgo Supercluster was considered our home at the largest scale. The 2014 discovery changed that. Virgo turned out to be one branch of something far larger.
How Astronomers Mapped Laniakea
Drawing a border around a supercluster is hard. Space has no walls, and galaxies are spread through an endless web of filaments. Earlier maps simply grouped together galaxies that looked crowded close to each other, so the borders were somewhat arbitrary.
Tully’s team took a different approach and followed the motion instead of the crowds:
- Measure distances. Using the Cosmicflows-2 catalog, they collected accurate distances to more than 8,000 galaxies.
- Remove the expansion of the universe. Every galaxy is carried away from us as space expands. Subtracting that effect leaves each galaxy’s “peculiar velocity,” its extra motion caused by the gravity of nearby matter.
- Trace the flows. Those motions reveal where gravity is pulling, including the pull of dark matter we can’t see directly. The team turned them into a 3D map of flow lines.
- Find the dividing lines. In some places neighboring galaxies flow in opposite directions. Those boundaries mark where one supercluster ends and the next begins.
It works like a watershed on Earth. Every raindrop that lands in a river basin ends up in the same river, even though the basin has no fence around it. Laniakea is a gravitational basin: every galaxy inside it is flowing toward the same place. The team published the result in Nature in September 2014.
Why It’s Called “Immeasurable Heaven”
The name was suggested by Nawa’a Napoleon, a professor of the Hawaiian language at Kapiʻolani Community College in Honolulu. Tully, who works at the University of Hawaiʻi, wanted the name to honor the Polynesian navigators who crossed the Pacific by reading the stars.
The words lani (heaven) and ākea (spacious, immeasurable) together give “immeasurable heaven,” a fitting name for something hundreds of millions of light-years wide.
The Great Attractor: Where Everything Is Flowing
Every galaxy in Laniakea, including the Milky Way, is drifting toward one gravitational low point, the Great Attractor. It lies about 150–250 million light-years away, in the direction of the southern constellations Norma and Centaurus.
Astronomers first noticed the pull in the 1980s, when they found that the Milky Way and its neighbors were moving through space faster and in a different direction than the expansion of the universe alone could explain. Our Local Group is moving at roughly 600 km/s, over 2 million km/h, relative to the background glow of the Big Bang.
Studying the Great Attractor is difficult because it sits behind the Zone of Avoidance, the part of the sky blocked by the dust, gas and stars of our own Milky Way. Astronomers have used X-ray and radio telescopes to see through it. They found a dense region of galaxies including the massive Norma Cluster, which seems to form part of the Great Attractor rather than being the whole story.
Laniakea’s Neighbors
Laniakea is surrounded by other superclusters, each with its own basin of flowing galaxies:
- Perseus–Pisces, a long chain of galaxies on the opposite side of the sky from the Great Attractor
- Coma, a massive supercluster built around the Coma Cluster
- Shapley, one of the most massive structures in the nearby universe, whose gravity pulls on Laniakea as a whole
The picture is still being refined. A 2024 study by members of the same research community, using larger catalogs of galaxy motions, suggested that Laniakea might itself be part of an even bigger basin of attraction centered on the Shapley Supercluster. Our cosmic address may yet get one more line.
Will Laniakea Hold Together?
No. Even though its galaxies all flow toward the same place, Laniakea is not held together by gravity the way a galaxy cluster is. The universe is expanding faster and faster, driven by dark energy, and over billions of years that expansion will pull Laniakea apart.
Smaller, tightly bound groups will survive. The Milky Way and Andromeda will stay together, but the other galaxy groups of Laniakea will slowly drift out of reach. In the far future, astronomers in our galaxy may not be able to see that Laniakea ever existed.
Laniakea in the Cosmic Web
Laniakea is one knot in the cosmic web, the largest pattern in the universe. Galaxies gather along long filaments and sheets, wrapped around enormous empty voids, and the filaments meet at dense clusters. On this scale the universe looks less like scattered dots and more like foam or a sponge.
The observable universe is about 93 billion light-years across, and it holds millions of superclusters like Laniakea. Our “immeasurable heaven” is just one neighborhood among them.
Keep exploring: Meet our biggest neighbor in You’re Looking 2.5 Million Years Into the Past When You See Andromeda, or zoom back in to the center of our own galaxy with Fermi Bubbles: The 50,000 Light-Year Scars Our Galaxy Can’t Hide.
Frequently Asked Questions
What is the Laniakea Supercluster?
Laniakea is the supercluster of galaxies that contains the Milky Way. It holds about 100,000 galaxies, spans roughly 500 million light-years, and was defined in 2014 by mapping the motions of more than 8,000 galaxies.
What does Laniakea mean?
Laniakea means “immeasurable heaven” in Hawaiian. The name was suggested by Hawaiian language professor Nawa’a Napoleon to honor Polynesian navigators.
Where is the Milky Way in Laniakea?
The Milky Way sits near the outer edge of Laniakea, inside the Local Group, which is part of the Virgo Supercluster, one of Laniakea’s branches.
What is the Great Attractor?
The Great Attractor is the gravitational center of Laniakea, about 150–250 million light-years away toward the constellations Norma and Centaurus. All galaxies in Laniakea, including ours, are flowing toward it. It is hard to study because the Milky Way’s own dust and stars block our view in that direction.