The Galileo spacecraft is the most sophisticated satellite ever to orbit another planet.

Since December 1995 it has sent back many stunning images of Jupiter and its curious retinue of moons. But no image is as strange as the ribbon of light seen threading through the atmosphere on the dark side of the planet.

Galileo has sent back stunning images of Jupiter

The band of light is hundreds of kilometres wide and circles, though is not centred on, the poles. It is tens of thousands of kilometres long.

The stream of light is caused by the same effect that generates light on a television screen.

Electrons are funnelled by Jupiter's intense magnetic field towards its magnetic poles.

As these cascades of charged particles strike the planet's upper atmosphere they cause it to glow, just as a TV screen glows when struck by a beam of electrons from behind.

The region above Jupiter's cloud decks is a turbulent place full of intense radiation.