Astronomers have discovered potentially the most massive black hole ever detected. The cosmic behemoth is close to the theoretical upper limit of what is possible in the universe and is 10,000 times heavier than the black hole at the center of our own Milky Way galaxy.

The black hole sits five billion light-years from Earth. It lies at the centre of a giant galaxy in the Cosmic Horseshoe system.

The black hole sits in one of two galaxies that make up the Cosmic Horsehoe, a massive system so large it bends light from a background galaxy into a distinctive horseshoe-shaped Einstein ring. The galaxy is a fossil group,