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.
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.