Dark matter distribution blue around the galaxy cluster ZwCl0024+1652 or Cl 0024+17. The ring measures 2.6 million light years across. This observation was the first time that dark matter was seen to have a distribution significantly different to that of the cluster in which it was found. The presence of the dark matter was inferred from its gravitational effects on the visible matter and background radiation, in a study published in 2007. The ring is thought to have been formed by the collision of two massive galaxy clusters. The cluster lies some five billion light years away from Earth in the constellation Pisces.