Oxygen makes Venus glow at night

This grey-scale image was taken on 3 June 2006 by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) onboard ESA’s Venus Express, at a distance of 68 000 kilometres from the planet’s surface.

The image shows the oxygen airglow in the night-side of Venus, appearing as the bright features similar to ‘clouds’ visible at the bottom of the image, and also visible as the white ring surrounding the planet’s disk (limb). The oxygen airglow is fully detectable only at specific infrared wavelengths. This image was obtained at 1.27 micrometres.

The fluorescence of the airglow is produced when oxygen atoms, ‘migrating’ from the day-side to the night-side of the atmosphere of Venus under the push of the so-called sub-solar and anti-solar atmospheric circulation, recombine into molecular oxygen (or ‘O2’) emitting light.

The view was obtained from south, with the south pole at the top of the image. The lower horizon is at about 20 degrees South latitude, while the image centre is at 60 degrees East longitude (coinciding with midnight local time).