Thunder Storms on Jupiter

On Jupiter, the colossal mesoscale convective complexes also last from 12 hours to several Earth days, producing correspondingly huge deluges of rain over vast areas. The new results show that - contrary to previous belief - these thunderstorm complexes are not fuelled by the Sun's heat, but instead develop from the intense heat emanating from Jupiter's core.

The giant planet lies five times further from the Sun than the Earth, so it receives much less solar heat. On the other hand, Jupiter's core is extremely hot. It still retains heat from the planet's original formation by collapse and compression of the planet's huge gaseous bulk. "It is in the process of cooling, and it will likely continue to cool for at least another five billion years," Gierasch says.

Heat leaks upwards from a reservoir of highly compressed hydrogen in the planet's center, so this gaseous giant emits nearly 70 percent more heat than it absorbs from the Sun. The source of the stormy turbulence on Jupiter thus seems to be the planet itself.

Mesoscale convective complexes on Earth are riven with lightning, seen dramatically from the space shuttle. What about Jupiter's giant storm systems? Galileo's instruments are not able to detect lightning on the planet's sunlit side. But once the storm crosses into the dark side, astronomers are able to see the lightning and confirm the existence of Jupiter's mesoscale convective complexes .

These lightning bolts dwarf anything on Earth, according to Andrew. P. Ingersoll of the California Institute of Technology and Blaine Little of ITRES Research, Calgary, Canada. They have measured the Jovian lightning strokes as several times the size of the largest terrestrial bolts.

Jupiter's storms are not only spectacular. The new Galileo results suggest that the mesoscale convective complexes provide the energy that drives the whole of Jupiter's powerful weather system. It's an almost-continuous cycle, Gierasch explains. The storms develop and drop rain; the raindrops evaporate prior to reaching Jupiter's core heat-source, and rise again as water vapour that convect upwards to start the next round of storms.

In the 400 years since the Italian astronomer Galileo first turned his telescope towards Jupiter, astronomers have puzzled over its spectacular bands and whorls of swirling clouds. Now the giant planet's secret is out. Its turbulent clouds and ferocious weather systems are fueled by its hidden superhot core, and driven by the greatest thunderstorms in the Solar System.

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