New analysis of images taken by ESA's Venus Express orbiter has revealed surprising details about the remarkable, shape-shifting collar of clouds that swirls around the planet's South Pole. This fast-moving feature is all the more surprising since its centre of rotation is typically offset from the geographical pole. The results of this study are published online in Science Express today.

Several planets in the Solar System, including Earth, have been found to possess hurricane-like polar vortices, where clouds and winds rotate rapidly around the poles. Some of these take on strange shapes, such as the hexagonal structure on Saturn, but none of them are as variable or unstable as the southern polar vortex on Venus. ...

Since the arrival of Venus Express in April 2006, high-resolution infrared measurements obtained by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument on Venus Express have revealed that the southern vortex is far more complex than previously believed. The VIRTIS images, taken at wavelengths of 3.8 and 5.0 microns, are ideal for tracking polar features on both the day and night sides of the planet, probing the polar cloud layer at an altitude of about 65 km...
Reported by the ESA website