NASA’s Cassini spacecraft eavesdropped on a storm on Saturn on March 15, 2011, by capturing pulses of radio waves from the lightning strikes, and sent back audio of the event.
First spied by amateurs in early December, this storm is the largest and most powerful to be observed in detail. Once spotted the storm grew dramatically, from 2,500 km across on the first day to 17,000 three weeks later, with a tail sweeping around the entire planet.
Instruments aboard Cassini recorded lightning strikes as fast as 10 per second, too fast for the spacecraft’s radio and plasma wave instrument to easily separate into individual signals. The team created this sound file from radio waves emanating from the storm on March 15, during a relatively calm period. The 11-second clip contains data gathered over 57 seconds.
Two teams of researchers describe the storm’s churnings in this week’s Nature. Storms large enough to be spotted by Earth-bound telescopes, occur on Saturn about once every 30 years and are dubbed Great White Spots — a play on Jupiter’s Great Red Spot.
Image: False-color images from NASA’s Cassini spacecraft of the huge storm raging on Saturn. (NASA/JPL-Caltech/Space Science Institute).