Scientists working with NASA's Cassini spacecraft said on Tuesday that the odd sounds received by Cassini indicate a largest ever thunderstorm on planet Saturn.

Those strange sounds were captured by the Cassini spacecraft when it witnessed a lightning storm on Saturn on January 23 and 24. The spacecraft has been orbiting Saturn and its moons since July 1, 2004.

The Cassini mission was managed by NASA's Jet Propulsion Laboratory based in Pasadena, California.

According to Bill Kurth of the University of Iowa, the deputy principal investigator for the radio and plasma wave science instrument, cracks and pops "heard" by a receiver on board Cassini were radio emissions generated by the lightning flashes.

"We're going to find out more about those sounds and what they mean...It's definitely a discharge process, a big spark that releases a lot of energy in a very short period of time," Kurth said.

"And a lot of work that was done on a similar phenomenon observed by Voyager 1 has led to the conclusion it must be lightning in the atmosphere," he said.

This wasn't the first time Cassini has witnessed lightning, but this was the biggest lightning storm, Kurth noted.

"Since we've been in orbit, we've detected maybe four or five such storms. This is by far the strongest that we've detected with Cassini," he said.

"And it's even stronger and there's more activity than the storms that were detected by the two Voyager spacecraft back in the early 1980s."

If people were actually in the atmosphere and listening, they would probably hear thunder when lightning goes off on Saturn, Kurth said.

"On the Cassini spacecraft, a long way away from the atmosphere, sound doesn't travel through the very tenuous gas surrounding the planets, but radio waves can."

"And so the radio waves from these lightning strokes would be detected by, for example, the AM radio on your car, and it would sound like cracks and pops that you hear when you drive through a thunderstorm here on Earth."

When the scientists first detected these radio emissions, they expected to see whether the storm actually happened. Amateur astronomers took images of Saturn that showed a cloud.

And that cloud, they believe, was under Cassini at the time when the radio emissions were detected.

"So we don't have proof, but we have a pretty good idea that this particular storm might be the storm that's associated with the lightning that we're detecting," said Kurth.

Source: Xinhua