Nightglow on Venus
7/22/11

Passionate about numerical simulations, Arnaud Collet has applied himself to the job of constructing a new model of the atmosphere of Venus, a step which has proven to be useful for solving the mystery surrounding the luminous phenomenon known as “airglow” which is produced there. The advance made thanks to this work has captured the attention of the Éditions Universitaires Européennes who have just decided to publish the work.

VenusIt was NASA’s Pioneer Venus mission that began exploration of the Venusian atmosphere. Launched in 1978 and operational up to 1992, the probe supplied the first almost complete mapping of the surface of our nearest neighbour, with an accuracy of up to 20 kilometres, as well as new observations of its winds and its atmospheric composition. In 2005, the first European mission to Venus was launched: Venus Express had a primary goal of investigating the atmosphere of Venus, but also its geology and surface.

The data gathered by Venus Express continues to be analysed at the present time. It has particularly allowed Arnaud Collet, a researcher in the Astrophysics, Geophysics and Oceanography department of ULg to construct a model of the atmosphere of Venus, because even though Venus is sometimes considered as Earth’s twin, the resemblance is nevertheless limited to the size of the planets. With regard to its atmosphere and climate Venus is radically different to our earthly oasis. Its atmosphere is composed of an opaque cloudy layer made up almost exclusively of carbon dioxide, with small quantities of sulphur dioxide. In such a hostile climate, life as it exists on Earth is impossible.

The Venus upper atmosphere, in particular that of the night side, reveals strange luminous emissions which constitute indirect indicators of the dynamics of its atmosphere. This phenomenon is called “airglow” and sometimes even “nightglow” when it is produced on the night side. We can indeed speak of a night side of Venus because the Venusian nights last almost two months, due to a particularity of the planet: its day (243 Earth days) is a lot longer than its year (223 days), put differently, Venus orbits the Sun faster than it rotates on its own axis.

Mission Venus

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