The lightning flashes were recorded as bluish spots in the middle of swirling clouds in a 2011 storm, the largest ever seen up close on the ringed planet, NASA's Jet Propulsion Laboratory reported Wednesday.
Scientists said the recently released images mark the first time lightning has been detected in visible wavelengths on the side of Saturn illuminated by the sun.
"We didn't think we'd see lightning on Saturn's day side -- only its night side," said Ulyana Dyudina, a Cassini imaging team member at the California Institute of Technology in Pasadena, Calif. "The fact that Cassini was able to detect the lightning means that it was very intense."
The intensity of the flashes is comparable to the strongest flashes on Earth, scientists said, with the visible energy alone estimated to be about 3 billion watts lasting for 1 second.
"As summer storm season descends upon Earth's northern latitudes, Cassini provides us a great opportunity to see how weather plays out at different places in our solar system," Linda Spilker, JPL Cassini project scientist, said. "Saturn's atmosphere has been changing over the eight years Cassini has been at Saturn, and we can't wait to see what happens next."