What Is the Great Attractor?
The short answer
The Great Attractor is a huge crowd of galaxies and dark matter, roughly 150 to 250 million light years away. Its gravity helps pull the Milky Way and its neighbors along at about 600 km/s, or about 1.3 million miles an hour. At its center is the Norma Cluster, about 220 million light years from us.
It isn't one object, and it isn't a black hole. It sits behind the disk of our own galaxy. Astronomers found it by watching how other galaxies move, then looked through the dust with X ray and radio telescopes.
Finding something you can't see
In 1986 and 1987, a team of astronomers nicknamed the Seven Samurai measured the motions of about 400 galaxies. They were all streaming the same way. Alan Dressler named whatever was pulling them the Great Attractor.
The trouble is where it sits. The Milky Way's stars and dust block a band of sky called the Zone of Avoidance. In visible light that band covers about a quarter of the whole sky, and the Great Attractor is right behind it.
Other kinds of light get through. The ROSAT satellite picked up X rays from the hot gas of the Norma Cluster, the 6th brightest galaxy cluster in its all sky survey. That gas puts the cluster's mass at roughly a million billion Suns. The Parkes radio survey, tuned to the 21 cm signal from hydrogen gas, found 883 galaxies hidden behind the disk.
The tow truck gets towed
The Great Attractor region is falling too. It is moving toward the Shapley Supercluster, a much bigger gathering of galaxies about 650 million light years away. One 2006 study split our motion in two: 44% from falling into the Great Attractor region, and 56% from mass farther out, with Shapley the largest single piece. A 2024 study found a slight preference for our whole neighborhood belonging to a much larger basin that drains toward Shapley. Astronomers still argue about the exact split in 2026.
Why we never get there
In 2014, astronomers mapped how about 100,000 nearby galaxies flow and named our supercluster Laniakea, Hawaiian for "immense heaven". The Great Attractor sits close to where those flows meet.
Laniakea isn't held together by its own gravity. The space between us and the Great Attractor keeps stretching faster than its pull can close the gap. So we keep falling toward it, and the distance keeps growing.
Key numbers
| What | Number | Source |
|---|---|---|
| Speed of the Milky Way measured against the cosmic microwave background | 565 km/s (about 1.26 million mph) | Planck Collaboration 2018 |
| Speed of the Local Group, our galaxy's small family, against the same background | 620 km/s (about 1.39 million mph) | Planck Collaboration 2018 |
| Our speed toward the Great Attractor | about 600 km/s (about 1.3 million mph) | BBC Sky at Night Magazine |
| Distance to the Great Attractor region | roughly 150 to 250 million light years | BBC Sky at Night Magazine |
| Distance to the Norma Cluster, at its center | about 220 million light years | ESA/Hubble, Picture of the Week potw1302a |
| Galaxies whose motions revealed the flow, measured in 1986 and 1987 | about 400 | Lynden-Bell et al. 1988, The Astrophysical Journal |
| Share of the sky hidden by the Milky Way's stars and dust, in visible light | about a quarter | Kraan-Korteweg & Lahav 2000 |
| Norma Cluster's X ray brightness rank among galaxy clusters in the ROSAT All Sky Survey | 6th brightest | Böhringer et al. 1996 |
| Mass of the Norma Cluster, from its X rays | about 10^15 Suns (estimates run from 0.4 to 2.2 × 10^15) | Böhringer et al. 1996 |
| Galaxies found behind the Milky Way's disk by the Parkes radio survey | 883 | Staveley-Smith et al. 2016 |
| Distance to the Shapley Supercluster | about 650 million light years | Wikipedia, Shapley Supercluster |
| Share of our motion from the Great Attractor region vs. mass farther out, in one study | 44% vs. 56% | Kocevski & Ebeling 2006 |
What the film simplifies
- The film says "over a million miles an hour." Measured against the cosmic microwave background, the Milky Way moves at 565 km/s (about 1.26 million mph), and the Local Group as a whole at about 620 km/s.
- The tow hook, cable, winch and chain are cartoon. Nothing is tied to anything: the pull is the combined gravity of thousands of galaxies and the dark matter around them.
- "Slip right through the dust" is rounder than the truth. Radio waves pass almost untouched. X rays get through far better than visible light, but some are still absorbed.
- The film shows the Great Attractor as the thing towing us. One study gives it only about 44% of our motion. The rest comes from mass farther out, and the exact split is still argued.
- "A whole stripe of the sky" has no number in the film because published estimates vary. One review puts it at about a quarter of the sky in visible light.
For teachers
Runtime 1 minute 11 seconds · Topics: Galaxies, Gravity, Expanding universe, Seeing through dust · Full script below
Ask your class
The Norma Cluster is about 220 million light years away and the Shapley Supercluster about 650 million. About how many times farther away is Shapley?
Answer
About 3 times. 650 divided by 220 is just under 3.
The Great Attractor is hidden behind the Milky Way's disk. Give two ways astronomers found out it was there.
Answer
They saw that nearby galaxies were all moving the same way, as if something was pulling them. Then X ray and radio telescopes, which see through dust far better than visible light, showed the Norma Cluster's hot gas and hundreds of hidden galaxies.
If the Great Attractor's gravity is pulling on us, why will we never reach it?
Answer
The space between us and it keeps stretching faster than its pull can close the gap. Our supercluster, Laniakea, isn't held together by its own gravity.
The script
Host: Something is dragging our whole galaxy across space.
Rocket: Free ride! Buckle up, Milky Way, where are we going?
Host: Toward something we can't even see. At over a million miles an hour.
Host: In the eighties, astronomers noticed the galaxies around us all drifting the same way.
Host: So they gave whatever's out there a name. The Great Attractor.
Rocket: The Great Attractor? Hey, that's what everyone calls me!
Host: One problem. It's hiding right behind our own galaxy.
Host: The Milky Way's stars and dust blot out a whole stripe of the sky.
Rocket: Hey, down in front! Some of us are trying to watch!
Host: So astronomers looked with X rays and radio waves, which slip right through the dust.
Lil Sat: Whoa! There's a giant crowd of galaxies hiding back there!
Gravity: Relax. It's just me. A whole lot of me.
Host: But get this. Whatever's towing us is getting towed too.
Host: By an even bigger pile of galaxies, way farther out.
Gravity: Hey! Who's pulling me?
Host: And we'll never get there. The universe is stretching faster than it can reel us in.
Rocket: A free ride that never ends? Best tour stop ever!
Host: Next stop: the day our Sun swells up and starts eating planets. Follow!
Sources
- Our galaxy moves about 565 km/s, over a million mph.Planck Collaboration 2018
- In the 1980s, astronomers found nearby galaxies streaming one way.Lynden-Bell et al. 1988, The Astrophysical Journal
- Our galaxy's stars and dust hide about a quarter of the sky.Kraan-Korteweg & Lahav 2000
- A giant galaxy cluster, Norma, sits hidden behind the Milky Way.Kraan-Korteweg et al. 1996, Nature
- X rays reveal the Norma Cluster's hot gas through the dust.Böhringer et al. 1996
- A radio survey found 883 galaxies behind the Milky Way's disk.Staveley-Smith et al. 2016
- The distant Shapley Supercluster also pulls on our galaxy's neighborhood.Kocevski & Ebeling 2006
- Cosmic expansion outpaces the pull, so we never arrive.Tully et al. 2014, Nature
- The Great Attractor is 150 to 250 million light years away; we move toward it at about 600 km/s; we'll never get there because Laniakea isn't gravitationally bound.BBC Sky at Night Magazine
- The Norma Cluster, at the heart of the Great Attractor, lies about 220 million light years away, behind the dust of the Milky Way's plane.ESA/Hubble, Picture of the Week potw1302a
- The Shapley Supercluster is about 650 million light years away, and the Great Attractor and our region are moving toward it.Wikipedia, Shapley Supercluster
- The Seven Samurai studied about 400 elliptical galaxies, and Alan Dressler named the Great Attractor.Wikipedia, Great Attractor
- Laniakea holds about 100,000 galaxies, its name is Hawaiian for "immense heaven", the Great Attractor is its focal point, and it isn't gravitationally bound.Wikipedia, Laniakea Supercluster
- There is a slight preference for our home basin, Laniakea, being part of a much larger Shapley basin of attraction.Valade et al. 2024, Nature Astronomy
- In 2026 astronomers still disagree about how much of our motion the Great Attractor causes.Stiskalek et al. 2026, The Open Journal of Astrophysics
- In 2026 astronomers still disagree about how much of our motion the Great Attractor causes (the other side).Dressler & Monson 2026 (preprint)