The Great Attractor is a gravitational anomaly in intergalactic space, at the centre of the local supercluster, which is drawing in galaxies over a region hundreds of millions of light years across.

These galaxies are all redshifted, in accordance with the 'Hubble flow', as if they were receding from us and from each other, but the variations in their redshift are sufficient to reveal the existence of a concentration of mass equivalent to tens of thousands of galaxies.

This phenomenon, which was discovered in 1986, lies at a distance of between 150 million and 250 million light years (250 million is the most recent estimate), in the direction of the Hydra and Centaurus constellations. In its vicinity there is a preponderance of large old galaxies, many of which are colliding with their neighbours, and/or radiating large amounts of radio waves.

It is dominated by the Norma cluster (ACO 3627), a massive cluster of galaxies. Attempts to study this and other phenomena further are hampered by its location, near the plane of our own Milky Way.