There is further, compelling evidence that Ganymede - the largest moon in the Solar System - has an ocean of water beneath its icy crust.

The new data comes from the Hubble Space Telescope, which has been studying how auroral lights dance around the satellite of Jupiter.

The presence of a sub-surface ocean would heighten interest in Ganymede as a potentially habitable world.

Europe's robotic Juice probe is being sent to orbit the moon in the 2030s.

Catharina Moh reports.