Paris under snow, Venus under clouds
Publiée le 2010-12-16
Paris under snow, Venus under clouds
Venus has an extremely dense atmosphere which acts like a barrier that prevents direct observation of its surface. However, at some wavelengths, we can probe the atmosphere of Venus, by looking at its dark side. For instance, observations in the wavelength of the near infrared spectral region, between 2.2 and 2.5 micron, are used to study cloud layers of the lower atmosphere (30-50 km of altitude).

Recent observations of Venus in this spectral range have been conducted from the Centre d'Observation à Distance en Astronomie à Meudon (CODAM), using the NASA 3m telescope IRTF, located at Mauna Kea, Hawaii. The images and spectra of the dark side of Venus were obtained during consecutive nights (13, 14 and 15 December 2010), in excellent weather conditions. The image here enclosed shows the crescent of Venus (Figure 1). On the dark side we can see the cloud formations in the lower part of the atmosphere. These images will allow the study of atmospheric circulation on the planet. Corroborated with spectra obtained concomitant with these images, studies will focus on the molecular composition of the clouds and the atmospheric chemistry of deeper layers.

Figure 1. The crescent and the night side of Venus as it was observed in December 13, 2010. The black, vertical line in the center of the image is the slit of the spectrograph. On the night side of the planet we can distinguish several clouds in the low atmosphere (30-50km of altitude). These clouds are accessible mainly to the K filter (2.2-2.5 microns).

Credit : Eliot Young, Mark Bullock(SWRI), Mirel Birlan, Marcel Popescu(IMCCE)

Contact: Mirel Birlan (

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