Call it a Saturnian version of the Ouroboros, the mythical serpent that bites its own tail. In a new paper that provides the most detail yet about the life and death of a monstrous thunder-and-lightning storm on Saturn, scientists from NASA's Cassini mission describe how the massive storm churned around the planet until it encountered its own tail and sputtered out. It is the first time scientists have observed a storm consume itself in this way anywhere in the solar system.

"This Saturn storm behaved like a terrestrial hurricane – but with a twist unique to Saturn,"
"Even the giant storms at Jupiter don’t consume themselves like this, which goes to show that nature can play many awe-inspiring variations on a theme and surprise us again and again."

The storm, first detected on Dec. 5, 2010, and tracked by Cassini's radio and plasma wave subsystem and imaging cameras, erupted around 33 degrees north latitude. Shortly after the bright, turbulent head of the storm emerged and started moving west, it spawned a clockwise-spinning vortex that drifted much more slowly. Within months, the storm wrapped around the planet at that latitude, stretching about 190,000 miles (300,000 kilometers) in circumference, thundering and throwing lightning along the way.

"This thunder-and-lightning storm on Saturn was a beast," said Kunio Sayanagi, the paper's lead author and a Cassini imaging team associate at Hampton University in Virginia. "The storm maintained its intensity for an unusually long time. The storm head itself thrashed for 201 days, and its updraft erupted with an intensity that would have sucked out the entire volume of Earth's atmosphere in 150 days. And it also created the largest vortex ever observed in the troposphere of Saturn, expanding up to 7,500 miles [12,000 kilometers] across."

This mosaic of images from NASA's Cassini spacecraft shows the trail of a great northern storm on Saturn raging in full force. The contrast in the images has been enhanced to make the turbulent parts of the storm (in white) stand out without losing the details of the surrounding regions. The head of the storm is the set of bright clouds near the left of the image. A clockwise-spinning vortex spawned by the storm shortly after it erupted in early December 2010 can be seen in the middle. The head of the storm moved very swiftly westward, while the vortex drifted more slowly westward.

A vortex that was part of a giant storm on Saturn slowly dissipates over time in this set of false color images from NASA's Cassini spacecraft. This clockwise vortex spun off the bright head of the storm shortly after the thunder-and-lightning storm erupted in early December 2010.

The top left image shows the vortex's most turbulent activity captured by Cassini's imaging cameras on Jan. 11, 2011. It was centered around 54 degrees west longitude and 35 degrees north latitude

NASA's Cassini spacecraft has tracked the aftermath of a rare massive storm on Saturn. Data reveal record-setting disturbances in the planet's upper atmosphere long after the visible signs of the storm abated, in addition to an indication the storm was more forceful than scientists previously thought.

Data from Cassini's composite infrared spectrometer (CIRS) instrument revealed the storm's powerful discharge sent the temperature in Saturn's stratosphere soaring 150 degrees Fahrenheit (83 kelvins) above normal. At the same time, researchers at NASA's Goddard Spaceflight Center in Greenbelt, Md., detected a huge increase in the amount of ethylene gas, the origin of which is a mystery. Ethylene, an odorless, colorless gas, isn't typically observed on Saturn. On Earth, it is created by natural and man-made sources.

Goddard scientists describe the unprecedented belch of energy in a paper to be published in the Nov. 20 issue of the Astrophysical Journal.

"This temperature spike is so extreme it's almost unbelievable, especially in this part of Saturn's atmosphere, which typically is very stable," said Brigette Hesman, the study's lead author and a University of Maryland scientist who works at Goddard. "To get a temperature change of the same scale on Earth, you'd be going from the depths of winter in Fairbanks, Alaska, to the height of summer in the Mojave Desert."

First detected by Cassini in Saturn's northern hemisphere on Dec. 5, 2010, the storm grew so large that an equivalent storm on Earth would blanket most of North America from north to south and wrap around our planet many times. This type of giant disturbance on Saturn typically occurs every 30 Earth years, or once every Saturn year.