Rare storm wreaking havoc on ‘normally calm’ Saturn

Cassini’s radio and plasma wave science instrument first detected the large disturbance.

Updated: May 20, 2011, 10:43 AM IST

Washington: NASA’s Cassini spacecraft and a European Southern Observatory ground-based telescope have tracked a rare storm in Saturn’s northern hemisphere.
The giant storm has been wreaking havoc for months and shooting plumes of gas high into the planet’s atmosphere.

Cassini’s radio and plasma wave science instrument first detected the large disturbance, and amateur astronomers tracked its emergence in December 2010.

As it rapidly expanded, its core developed into a giant, powerful thunderstorm. The storm produced a 5,000-km-wide dark vortex, possibly similar to Jupiter’s Great Red Spot, within the turbulent atmosphere.

The dramatic effects of the deep plumes disturbed areas high up in Saturn’s usually stable stratosphere, generating regions of warm air that shone like bright ‘beacons’ in the infrared.

“Nothing on Earth comes close to this powerful storm,” said Leigh Fletcher, the study’s lead author and a Cassini team scientist at the University of Oxford in the United UK.

“A storm like this is rare. This is only the sixth one to be recorded since 1876, and the last was way back in 1990,” he added.

This is the first major storm on Saturn observed by an orbiting spacecraft and studied at thermal infrared wavelengths, where Saturn’s heat energy reveals atmospheric temperatures, winds and composition within the disturbance.

The violence of the storm -- the strongest disturbances ever detected in Saturn’s stratosphere -- took researchers by surprise. What started as an ordinary disturbance deep in Saturn’s atmosphere punched through the planet’s serene cloud cover to roil the high layer known as the stratosphere.

Details of the findings are published in the current edition of Science Magazine.