ESA Science & Technology - Science Poster - Venus Express Results

TOP:
This ultraviolet image of Venus at 380 nanometres was taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on 19 April 2006, during the capture orbit around the planet, from a distance of about 190 000 kilometres.  In the day side (top half) it is possible to see interesting atmospheric stripe-like structures.  Spotted for the first time by Mariner 10 in the 1970s, they may be due to the presence of dust and aerosols in the atmosphere, but their true nature is still unexplained.

BOTTOM:
This sequence of images was taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) between 12 and 19 April 2006, during the capture orbit around Venus.  The false-colour images were obtained at six different time slots and different distances from the planet (from left to right, top to bottom): 

• 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

Each image is the composite of the day side of Venus (left, in blue, taken in ultraviolet light at 380 nm) and the night side (right, in red, taken in infrared light at 1.7 μm).

The ultraviolet part shows solar radiation reflected by the atmosphere.  The infrared part shows complex cloud structures, revealed by the thermal radiation coming up from different atmospheric depths.  Venus Express can resolve these structures by use (for the first time from orbit) of the infrared windows present in the atmosphere of Venus.  In fact, if observed at certain wavelengths, it is possible to detect thermal radiation coming from the deepest atmospheric layers, revealing what lies beneath the dense cloud layers situated at about 60 kilometres altitude.

In the colour scheme of the presented infrared images, the brighter the colour, the more radiation comes up from the lower layers.