National Geographic News
Two views of a solar tornado.

Video stills of the solar tornado, as seen by a NASA satellite.

Images courtesy Xing Li, University of Aberystwyth/NASA

Andrew Fazekas

for National Geographic News

Published March 29, 2012

A monster "tornado" big enough to swallow a hundred Earths has been spied on the sun, according to astronomers who analyzed recent images from NASA's Solar Dynamics Observatory.

Watch video of the solar tornado at a wavelength of 171 angstroms:

Video courtesy NASA/Goddard/Li/University of Aberystwyth.

Known as solar prominences, such tornado-like structures have been observed on the sun for decades. But the latest solar twister is one of the biggest yet seen—and likely the first to be filmed in high-resolution at multiple wavelengths.

(Also see "Giant 'Tornadoes' Seen Erupting From the Sun.")

"The structure is huge ... and the velocity of the material is several tens to hundreds of thousands of kilometers per hour," said Xing Li, an astronomer at Aberystwyth University in Wales, who co-authored a new study describing the vortex.

"It is a real gem of an event to fire the imagination—and it is a good way to study magnetic structures in the sun's atmosphere."

Solar Spirals Often Erupt

Visually, the 124,000-mile-tall (200,000-kilometer-tall) solar twister resembles one of its Earthly counterparts, Li said. But the sun tornado was created by an entirely different mechanism.

On Earth, twisters form when a rising column of warm, moist air begins rotating due to intense wind shear associated with large thunderstorms.

The titanic solar events, meanwhile, are caused by spiral-shaped magnetic structures that rise from the sun and are rooted to the solar surface at both ends.

A sun tornado starts when a huge injection of plasma—charged, superheated gas—happens to shoot up one of the structure's legs. The plasma is guided along the helical shape of the structure's magnetic field, giving rise to a coherent rotation of material, Li said.

(Also see "'Dark Fireworks' Seen on Sun—Blast as Big as Ten Earths.")

Watch video of the solar tornado at a wavelength of 193 angstroms:

Video courtesy NASA/Goddard/Li/University of Aberystwyth.

While this particular sun tornado didn't produce any plasma eruptions, other types of solar prominences are often seen to erupt spectacularly, sending giant clouds of charged particles flying off into space.

When these electrically charged clouds, known as coronal mass ejections (CMEs), are aimed at Earth, the solar particles can disrupt both ground- and space-based technologies and can trigger colorful aurora displays.

(See pictures: "Multicolored Auroras Sparked by Double Sun Blast.")

"We do not understand yet why this particular event gave us such a spectacular show for several hours [but] did not erupt," Li said.

"Perhaps this is rare, but it's perhaps the fact that most such structures are unstable and erupt as CMEs [that] is the reason we don't usually see many solar tornadoes."

Sun Tornado's Ethereal, Strange Dance

Ultimately, Li believes further study of solar tornadoes will help scientists understand space weather and the causes of space storms in general.

(Related: "Solar Flare Sparks Biggest Eruption Ever Seen on Sun.")

"It is the beauty of this tornado which has grabbed us—the ethereal, strange dance of blobs of plasma trapped in the sun's tangled magnetic field," Li said.

"When we saw this event, we were astounded and were instantly hooked. We are now putting every effort into understanding what we were seeing."

The solar-tornado study was presented this week during the 2012 National Astronomy Meeting in Manchester, England.

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