A restless 'hurricane eye' morphs and changes shape within days at the south pole of Venus, according to observations from the Venus Express spacecraft.
The core of the gigantic vortex glows brightly in thermal infrared, suggesting that turbulent atmospheric gases are sinking downward and making the region hotter.
?Simply put, the enormous vortex is similar to what you might see in your bathtub once you have pulled out the plug? said Giuseppe Piccioni, a Venus Express scientist in Rome, Italy.
The study of this phenomenon first appeared in the November 2007 issue of the journal Nature. Scientists released new images of the storm this week.
The 1,240-mile-wide vortex (2,000 km) can shift in 24 hours from an eye shape to an hour-glass shape, and at other times appears oval. The whole structure resembles a rapidly changing hurricane eye as seen on Earth, with some differences.
"The main difference is that the Venusian vortex is upside down with respect to the [Earth] hurricane, meaning that the vertical air flow of the hurricane is down-top [meaning air flows inward at the bottom of a storm and then up through the storm] while the Venusian one is top-down," Piccioni told SPACE.com.
The Venus vortex also differs from Earth hurricanes because of its monstrous planetary scale, and it is probably permanent, according to Piccioni.
A mystery still surrounds how the vortex formed in the first place. The atmospheric gases flow dynamically in different directions and at different altitudes.
?One explanation is that atmospheric gases heated by the Sun at the equator, rise and then move poleward," said Colin Wilson, a Venus Express scientist at the University of Oxford, Great Britain. "In the polar regions, they converge and sink again. As the gases moves towards the poles, they are deflected sideways because of the planet?s rotation.?
Scientists have long observed Venus' wacky weather features. The 'hurricane eye' was discovered in 1974 by the Mariner 10 spacecraft. A similar structure exists on the planet?s north pole, which was observed by the Pioneer Venus mission in 1979.
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