spacetoday.net: Cassini detects lightning, radiation belt at Saturn

Posted: Sun, Aug 8, 2004, 10:06 AM ET (1406 GMT)
Cassini enters orbit around Saturn (NASA/JPL)

NASA's Cassini spacecraft has observed lightning in the atmosphere of Saturn and also discovered a new radiation belt surrounding the planet, scientists announced Thursday. Cassini's radio and plasma wave science instrument discovered the lightning indirectly, by detecting the radio waves generated by the lightning, much like the sounds that can be heard on AM radios during lightning storms on Earth. The amount of lightning varies from day to day, in sharp contrast to data from the Voyager flybys over 20 years ago, when the level of lightning outbursts was relatively constant over months. Differences in lighting conditions caused by the relative position of the shadow cast by the planet's rings may be the cause for the difference in lightning levels. Cassini has also discovered a radiation belt extending around the planet inside the rings and just above the cloudtops in the atmosphere. The belt is far closer to the planet than what scientists thought could exist.