Venus South Pole Roils With Fickle Storm

March 17, 2008 -- With its choking carbon dioxide atmosphere, thick clouds of sulfuric acid and lead-melting heat, Venus has been a living laboratory for meteorologists fascinated by wild weather. Among the most provocative storms are massive hurricanes over the planet's north and south poles.

The systems are not only long-lived -- they were first spotted more than 30 years ago by NASA's Mariner and Pioneer spacecraft -- but fickle. Scientists have discovered that the eye of the south pole storm, which is centered in a 2,000-kilometer (1,243-mile) wide vortex, can change its shape within days.

It is not yet known if its sister storm in the north is doing the same.

The finding, announced this week by the European Space Agency, is based on infrared images taken by Europe's Venus Express spacecraft, which has been studying Earth's sister planet for almost two years.

One picture, taken Feb. 26., shows a classic hourglass-shaped structure in the south pole vortex, nearly identical to previous findings. Another image taken just 24 hours earlier however, shows the structure at the center of the vortex, which is similar to the eye of a hurricane, to be nearly circular.