The Great Attractor isn't a black hole. Even the universe's most gargantuan black holes are mere specks compared to this vast cosmic valley where 100,000 galaxies are falling.
It is actually the gravitational focal point of a colossal web known as the Laniakea Supercluster. To understand why it cannot be a single object, consider the scale. The Great Attractor is pulling in galaxies, including the Milky Way, across a span of hundreds of millions of light-years. The mass required to exert that much gravitational influence is estimated at tens of thousands of times the mass of the entire Milky Way. A single black hole with that much mass would disrupt surrounding space in ways astronomers do not observe.
For decades, the true nature of the Great Attractor remained a mystery because it sits in the "Zone of Avoidance"—a region of the sky heavily obscured by the dense gas and dust of the Milky Way's galactic plane. Visible light telescopes could not see what was pulling the galaxy.
When astronomers finally peered through the dust using X-ray and radio astronomy, they did not find a single monolithic object. Instead, they found massive concentrations of galaxies and dark matter, particularly the Norma Cluster. By mapping the motion of galaxies in the local universe, researchers realized that the Milky Way is just one droplet in a vast cosmic watershed.
The Great Attractor is simply the bottom of this gravitational basin. Just as water flows down mountainsides to pool in a valley, galaxies within a 500-million-light-year radius are all "flowing" along filaments of dark matter toward a common center of mass. The Attractor is a location—the densest point of convergence—rather than a discrete object.
Yet, even this colossal accumulation of mass is not the end of the line. The entire Laniakea Supercluster, including the Great Attractor, is actively being pulled toward an even larger concentration of galaxies further out in the universe, the Shapley Supercluster.