What is causing the great attractor in the universe?

 An unseen mass is dragging the Milky Way through space at 1.3 million mph. But when astronomers finally peered through the cosmic dust, they found the Great Attractor wasn't the true culprit.

When researchers first mapped this cosmic drift in the 1970s, they named the gravitational anomaly pulling the local universe the Great Attractor. For decades, it remained a mystery because it sits in a region of the sky called the Zone of Avoidance. The anomaly lies directly behind the dense central plane of the Milky Way, where gas, dust, and stars block visible light and act as a blindfold.

Once astronomers began mapping the sky using X-ray and radio telescopes—which can peer through the galactic dust—they found the initial suspect. At the heart of the Great Attractor lies the Norma Cluster (Abell 3627), a dense concentration of thousands of old, colliding galaxies located about 150 million light-years away. It sits near the center of the Laniakea Supercluster, the immense web of galaxies that contains the Milky Way.

However, the Norma Cluster alone does not have nearly enough mass to account for the immense gravitational pull on the local universe. It turns out the Great Attractor is just a localized accumulation of matter being pulled by something even larger.

Farther out, roughly 650 million light-years away and directly behind the Great Attractor, lies the Shapley Supercluster. This behemoth contains more than 8,000 galaxies and represents the most massive concentration of matter within a billion light-years of Earth. The Shapley Supercluster is the true cosmic anchor. Its gravity is pulling the Great Attractor toward it, and the Great Attractor is dragging the Milky Way along for the ride.

A composite view of the core of the Shapley Supercluster, combining Planck observations of diffuse gas in blue with ROSAT X-ray data of hot gas within the clusters in pink. Photo by ESA & Planck Collaboration is licensed under CC BY-SA 3.0.

What is the Great Attractor?

 The Great Attractor is a large region of space where an unusually high concentration of matter produces a strong gravitational influence on the motion of thousands of galaxies, including our own Milky Way.

It is located roughly 150–250 million light-years away, in the direction of the constellations Norma and Centaurus.

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Despite its name, the Great Attractor is not a single object. It is not a giant black hole or some mysterious cosmic object pulling everything toward it. Instead, it is associated with a large concentration of galaxies, galaxy clusters and dark matter.

Astronomers discovered its existence by studying the motion of galaxies. The expansion of the Universe causes galaxies to move away from one another, but gravity creates additional motions called peculiar velocities. Many galaxies in our region of the Universe have motions that indicate they are being influenced by large concentrations of matter in this direction.

Studying the Great Attractor is difficult because it lies behind the Zone of Avoidance, where the dense stars and dust of our own Milky Way obscure observations of distant galaxies.

The Great Attractor is also not the final or only gravitational influence on our cosmic neighbourhood. It forms part of the much larger Laniakea Supercluster, and even more distant structures, including the Shapley Supercluster, contribute to the motions of galaxies in our region.

So, scientifically speaking, the Great Attractor is best understood not as a single cosmic object, but as a large-scale concentration of matter whose gravity significantly influences the movement of galaxies across hundreds of millions of light-years.

And no, the Milky Way is not being dragged toward it like a spaceship toward a black hole. The motion of galaxies results from the combined effects of cosmic expansion and the gravitational field of the large-scale structure of the Universe.

What is the Great Attractor drawing all the galaxies towards it?

 Right now, the Milky Way and 100,000 other galaxies are hurtling at 1.3 million mph toward a massive gravitational anomaly. But the Great Attractor isn't the final destination.

For decades, the Great Attractor was an astrophysical mystery because of its location. It sits about 150 to 250 million light-years away in the Centaurus Supercluster, placing it right in the "Zone of Avoidance." This is the band of sky obscured by the dense gas, dust, and stars of our own Milky Way's galactic plane, which blocks visible light from beyond it.

When astronomers finally peered through this dust using X-ray and radio telescopes, they found a dense concentration of mass dominated by the Norma Cluster. The Norma Cluster is a dense gathering of old, massive galaxies, but its visible matter alone is not enough to generate the immense gravitational pull required to drag our entire corner of the universe toward it. The vast majority of the Great Attractor's mass consists of dark matter, the invisible substance that makes up the bulk of the universe's gravitational scaffolding.

A map of the Laniakea Supercluster and its surrounding galaxy clusters Photo by Andrew Z. Colvin is licensed under CC BY-SA 4.0.

The Great Attractor acts as the gravitational center of the Laniakea Supercluster, the immense web of galaxies that includes our own. Think of Laniakea as a vast watershed, with the Great Attractor as the basin at the bottom of the valley. The galaxies within this structure are like water flowing down the cosmological slopes toward the lowest point.

In the 2000s, astronomers mapping the large-scale structure of the universe realized that the Great Attractor itself is moving. It, along with the rest of Laniakea, is being pulled toward an even more colossal structure located 650 million light-years away: the Shapley Supercluster. This gargantuan region contains more than 8,000 galaxies and has a mass thousands of times greater than the Milky Way, making it the most massive galaxy cluster within a billion light-years of Earth.

What if the Great Attractor was a gigantic black hole 100x larger than the TON 618?

 

A cool what-if, but that is not reality.

100x larger than TON 618 is peanuts compared to what's actually tugging on our galaxy.

TON 618 already is considered a monster, at 66 billion solar masses for black holes, yes.

Times that by 100?

You're looking at 6.6 trillion solar masses.

Impressive, but the Great Attractor is dragging on stuff with the equivalent of 100 quadrillion solar masses.

Or about 15,000 times more massive than your hypothetical black hole.

We are also fairly pretty sure that the Great Attractor is not an object.

Probably an enormous super-cluster of galaxies, right in the middle is the Norma Cluster.

We can hardly see it because it lies behind the galactic centre of the Milky Way, but its gravitational effects leave no doubt.

It is huge enough to take part in tens of thousands of galaxies, even whole clusters, in motion.

A black hole-even one 100 times bigger than TON 618-just doesn't have that kind of reach, doesn't have that heft.

The real Great Attractor is that huge knot in the cosmic web where galaxies, dark matter, and everything else flow into.