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.
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.