Electrical discharges 10,000 times more powerful than lightnings on Earth

Apr 30, 2008 07:31 GMT  ·  By

When it comes to gas giants, nothing is small. This also applies in the case of the electrical storm dominating the southern areas of Saturn for the last five months or so, the longest storm recorded to date and capable of producing lightning discharges some 10,000 times more powerful than those observed on Earth.

"We saw similar storms in 2004 and 2006 that each lasted for nearly a month, but this storm is longer-lived by far. And it appeared after nearly two years during which we did not detect any electrical storm activity from Saturn", said Georg Fischer, Cassini associate and radio and plasma wave scientist at the University of Iowa.

The first evidence that a storm is about to start came on November 27, 2007 when the radio and plasma wave science instrument on board the Cassini probe recorded lightning signals. Six days later the spacecraft caught the first optical pictures of the storm developing inside Saturn's thick atmosphere. "The electrostatic radio outbursts have waxed and waned in intensity for five months now", explained Fischer.

Basically the electrical discharges on Saturn are much like those occurring regularly on Earth, but much more powerful and longer in length, covering distances up to several thousand kilometers and being able to generate extreme electromagnetic emissions in the radio wavelengths. Such a discharge was observed by the Cassini investigation team back in 2004, which gave it the generic name "The Dragon".

Electrical storms on Saturn are most often spawned in the so called "Storm Alley", a portion of the Saturnian atmosphere where violent storms are frequently generated. The radio emissions can be so strong that Cassini is able to detect them even when the storm is out of direct view. Aside from sharing many of the characteristics of Earth's electric storms, Saturn's season change also seems to be affecting the lightning patterns.

"In order to see the storm, the imaging cameras have to be looking at the right place at the right time, and whenever our cameras see the storm, the radio outbursts are there", says Ulyana Dyudina, Cassini imaging team associate from the California Institute of Technology. Cassini makes a complete orbit around the planet once every 10 hours and 40 minutes, tracking the storm every time it comes into view although it can be observed from Earth as well.

"Since Cassini's camera cannot track the storm every day, the amateur data are invaluable. I am in continuous contact with astronomers from around the world", says Fischer.