An ultra-massive black hole, 36 billion times the Sun’s mass, hides in the Cosmic Horseshoe galaxy 5 billion light-years away, unveiled by a perfect Einstein Ring and precise stellar motion measurements.

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

Theoretically, there's no limit to how massive a black hole could grow. In practical terms, other constraints, such as the growth rate, suggest that the maximum mass a black hole could achieve within the current 13.8-billion-year lifespan of the Universe is about 50 billion solar masses.