The left image was taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express on 29 May 2006, from a distance of about 64 000 kilometres from the planet. The vortex is imaged at a 5.05-micron wavelength, corresponding to an atmospheric altitude of about 59 kilometres, just about the Venusian cloud deck.

The right image was taken in October 2006 by the Visual Infrared Mapping Spectrometer (VIMS) on board NASA’s Cassini, at a 5-micron wavelength. The large number of dark, circular leopard spots indicates that convective activity extending over dozens of kilometres in altitude is surprisingly rampant in the south polar region. Literally hundreds of storm clouds encircle the pole, appearing as dark spots in this image. Each of these spots represents a storm.

Credits: NASA/JPL/Space Science Institute/University of Arizona

The frames have been aligned to make the planet appear stationary, while the Sun appears to revolve about the pole in a counter-clockwise direction. The clouds inside the dark, inner circle are lower than the surrounding clouds, which cast a shadow that follows the sun.

The South polar storm, which displays two spiral arms of clouds extending from the central ring and spans the dark area inside a thick, brighter ring of clouds, is approximately 8000 kilometres across, which is considerably larger than a terrestrial hurricane.

Image scale is about 17 kilometres per pixel. The images were taken with the wide-angle camera using a spectral filter sensitive to wavelengths of infrared light centred at 0.752 microns. All frames have been contrast enhanced using digital image processing techniques. The unprocessed images show an oblique view toward the pole, and have been re-projected to show the planet from a perspective directly over the South pole.

Credits: NASA/JPL/Space Science Institute

The sequences (taken at 5 microns) were obtained during six different time slots and at different distances from Venus:

• 12 April: from 210 000 kilometres
• 13 April: from 280 000 kilometres
• 14 April: from 315 000 kilometres
• 16 April: from 315 000 kilometres
• 17 April: from 270 000 kilometres
• 19 April: from 190 000 kilometres

Around the South pole it is possible to see a peculiar double-eye vortex structure, never clearly seen by any other Venusian mission before. The movie shows the rotation and the shape variation of the double vortex over time. It is also possible to see the rotation of the ‘terminator’, the line separating the day side – visible in yellow - from the night side.

The images also show the presence of a collar of cold air around the vortex structure (dark blue), possibly due to the recycling of cold air downwards.

Credits: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

The four monochrome images displayed here were acquired by the Imaging Science Subsystem (ISS); the blue and red images in the bottom row were taken by the Visual and Infrared Mapping Spectrometer VIMS). The images are arranged in order of increasing wavelength in nanometers as follows: (top row) 460 nm, 752 nm, 728 nm; (bottom row) 890 nm, 2,800 nm, 5,000 nm.

At the centre of the cauldron of storms spinning around the South pole is the South pole itself, which literally appears to be the eye of this vast polar storm system. As in a hurricane on Earth, the south polar ‘eye’ is relatively clear of clouds and is surrounded by a wall of towering clouds that cast shadows into the centre. However, while morphologically similar, it is not clear if this vortex operates in the same fashion as a terrestrial hurricane.

Literally hundreds of storm clouds encircle the pole, appearing as dark spots in the infrared spectrometer thermal image (red image) and as both bright and dark spots in images taken in sunlight (blue image). Each of these spots represents a storm. These pictures reveal that Saturn's south pole is a cauldron of storm activity.

Credits: NASA/JPL/Space Science Institute/University of Arizona