Two enormous storms on the surface of Jupiter have provided important clues about the true nature of the solar system's biggest planet, astronomers say.

Professor Agustin Sánchez-Lavega from Universidad País Vasco in Spain and colleagues report their findings in today's issue of the journal Nature.

Jupiter's atmosphere is wreathed in a blanket of thick cloud that prevents telescopes from observing deeper into the planet.

Among the only clues are occasional storms, which burst through this cloud layer and appear as light patches within the planet's characteristic stripes.

"The main thing the modelling showed was that there seems to a jet stream effect below the influence of the sun," says Valimberti.

"That indicates it is being generated by something internal within the planet, some kind of internal heat source."