Clouds over Alpha Regio on Venus

This image of the Venusian south polar region was acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from a distance of about 65 000 kilometres from the planet’s surface.

The image, showing a complex cloud system, was taken on the night-side of Venus (04:00 local time), at a wavelength of 1.7 micron that allows viewing the deep atmospheric layers. The field of view covers an area located at approximately 20 degrees west longitude (diagonal top left to bottom right), spanning from the equator (at the horizon on the right) to 60 degrees southern latitude (top left corner of the image).

The grey-scale of the images is such that white signifies more transparency, therefore less clouds, while darker or blacker regions represent opacity, or thicker clouds.

The Alpha Regio area is at the bottom left of the image. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 kilometres high. It is not yet clear if atmospheric turbulences may be induced by the rough topography below the clouds.