Astrophysicists have witnessed the rare event of a black hole awakening from its slumber to snack on a planet-sized object in a galaxy 47 million light years away, the University of Geneva says.

The observation made using the European Space Agency's Integral satellite project, revealed a black hole that had been slumbering for years chomping on a giant, low-mass object that had come too close.

Swiss scientists have seen a black hole wake up and eat an object with a mass 15 times that of Jupiter. Credit:Gabriel Perez Dia

Integral was launched in 2002 to study gamma rays and throw light on events far from Earth's galaxy.

Scientists working on the project spotted a light flare coming from a black hole in the centre of the NGC 4845 galaxy, which has a mass more than 300,000 times greater than the Sun and has been dormant for more than 30 years, the university said.