NASA Probe Spies Giant Hurricane on Saturn

New views of the gas giant's hurricane will shed light on similar storms on Earth.

A monster-size hurricane raging around Saturn's north pole has come into focus, thanks to NASA's Cassini spacecraft, and researchers hope it will help shape our understanding of similar storms on Earth.

"Morphologically, this giant storm resembles that of hurricanes and typhoons on Earth—with an eye at its centre and spiralling clouds outside—but this Saturnian hurricane is on a titanic scale," said Kunio Sayanagi, a Cassini imaging team member at Hampton University in Virginia.

Just the eye of the storm is estimated to stretch 1,250 miles (2,000 kilometres) across—more than 20 times larger than hurricanes that swirl on Earth. 

Scientists aren't sure when the hurricane formed, but speculate that it could be a permanent weather feature, said fellow Cassini imaging team scientist Andrew Ingersoll at the California Institute of Technology in Pasadena.

When Cassini first arrived at the gas giant in 2004, the planet's northern hemisphere was deep in winter, with its north pole tilted away from the sun and shrouded in darkness. But the orbiter's two infrared cameras—which act like night-vision goggles—were able to pierce through the polar night and capture the first hints of the massive storm's existence.

With the eye of the storm being an actual hole in the clouds, the deeper, warmer layers of Saturn's atmosphere were exposed, showing up on the cameras as a tell-tale thermal emission, said Sayanagi.

"These cameras don't have very high resolution, but still saw a [infrared] hotspot at the pole earlier in the mission, which we found interesting," he explained.

Springtime for Saturn's northern hemisphere arrived in 2009, but Cassini researchers weren't able to get the spacecraft into the proper orbit to take pictures of the hurricane with optical cameras until November 2012.

A New View

The newly released batch of stunning photos, taken with the optical cameras under daylight conditions, now showcase the beauty and intricate structure of the hurricane in visible wavelengths.

Cassini scientists believe these new views will begin to shed light on the inner workings of not only this Saturnian hurricane, but also its smaller cousins here on Earth. (Learn about hurricanes on Earth.)

On Earth, hurricanes feed off of evaporated water droplets from warm tropical seas. But Saturn has no oceans, so how the ringed planet's atmosphere drives hurricane formation is a mystery.

The hurricane's location—locked at Saturn's north pole—is also puzzling. On Earth, hurricane movements tend to start at tropical equatorial regions and glide northward due to forces acting on the storm as the planet rotates.

Meanwhile, colour-enhanced images of Saturn's hurricane show wispy clouds along the eye's wall whipping around at speeds of 330 miles per hour (540 kilometres per hour). Even stronger winds are possible moving out from the wall.

A Hurricane's Guts

Similar hurricane-like storms have been seen on other gas giants in our solar system. But what has stumped scientists is why wind speeds get cranked up the farther out we move in the solar system, said Caltech's Ingersoll. 

This may seem counterintuitive, but it might have to do with the atmospheres on these outer planets being less turbulent than Earth's atmosphere, he explained.

Both water vapour and less atmospheric turbulence make for more powerful hurricanes.

Like other gas giants, "Saturn has a deep hydrogen atmosphere with little water vapour in it, yet somehow it produces high winds anyway," Ingersoll said.

The Cassini team believes that Saturn offers a unique laboratory to study hurricanes, which they hope will help unlock some of the mysteries of water's role in powering such strong winds.

"Earth is complicated and messy because hurricanes interact with changing ocean temperatures, run into coastlines, get nudged around by jet streams, and these factors make it really hard to study the basic underlying principles that drive a hurricane," explained Sayanagi.

In contrast, this newly discovered Saturnian hurricane does not encounter land-ocean boundaries and is stationary at the pole, allowing researchers to simply focus on the physics that govern hurricanes.

"This is the kind of setup we can really use to push our limits on our understanding of how hurricanes work, and the best part is that nobody is getting hurt by this extreme hurricane as we study it," added Sayanagi.

Header Image: A high-resolution picture of a large hurricane over Saturn's north pole, taken by NASA's Cassini spacecraft. IMAGE COURTESY CALTECH/NASA

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