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Last Updated: Friday, 23 July 2004, 14:01 GMT 15:01 UK
Cassini sees lightning on Saturn
By Paul Rincon
BBC News Online science staff, in Paris

Artist's impression of Cassini in orbit around Saturn, Nasa
The lightning can tell scientists more about the atmosphere and wind velocities on the planet
The Cassini space probe has observed lightning in Saturn's atmosphere.

The probe detected radio wave emission from storms, which varied with the planet's latitude and rotation.

This is the first direct observation of lightning in Saturn's atmosphere, although the Voyager probe made an indirect detection in the 1980s.

Scientists now hope to use the same method to detect lightning on Saturn's largest moon, Titan, when the probe makes a close flyby in October.

The lightning can tell scientists more about the atmosphere and wind velocities on the planet.

"We have observed several storms and used direction finding to detect their origin with good radio wave resolution," mission scientist Phillippe Zarka told the Committee on Space Research (Cospar) scientific assembly.

Radio emission

The radio emission was detected by Cassini's radio and plasma wave science instrument (RPWS).

"This is good confirmation that what we have is lightning from Saturn's atmosphere."

The detection was made during the probe's closest approach to the planet on 1 July.

Cassini's magnetospheric imager has also detected a new radiation belt around Saturn's rings.

The planet's main radiation belt extends far outside the main ring system. The new belt sits within the rings and extends right around the planet.

Cassini makes a close flyby of Titan on 26 October.

"This will give us good information of the existence of lighting - or not - on Titan," said Dr Zarka.

Recent images of Titan did not show clear evidence of oceans composed of hydrocarbons on the surface - as some scientists have suggested there might be.

But one new hypothesis suggests that the oceans may be covered from view by some sort of hydrocarbon fog.


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