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| A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
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Atmosphere of Venus
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| Artist's impression of the surface of Venus
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Recommended books |
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Venus' atmosphere consists almost entirely (97%) of carbon dioxide, with clouds containing droplets of sulfuric acid along with compounds of chlorine and fluorine. These precipitate an acid rain called virga, which evaporates before it has the chance to reach the surface. In the upper part of the atmosphere, clouds swirl by at a rate of 300 km/h, driven by fierce winds.
| Atmospheric composition at surface level |
Major components (by volume) 96.5% carbon dioxide (CO2) 3.5% nitrogen (N2) Minor components (parts per million) 150 sulfur dioxide (SO2) 70 argon (Ar) 20 water vapor (H2O) 17 carbon monoxide (CO) 12 helium (He) 7 neon (Ne) |
| Surface pressure | 92 bars |
| Surface density | ~65 kg/m3 |
| Surface wind speeds | 0.3-1.0 m/s |
 © 2005 Pearson Prentice Hall, Inc |
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History of observations
That Venus was permanently enveloped in what appeared to be thick, white clouds soon became clear following the development of the telescope. By analogy with the Earth, it was generally assumed that these clouds were made of water vapor, a conclusion supported by early spectroscopic studies by Secchi. The main composition of the atmosphere remained a matter for conjecture until spectroscopic observations by Walter Adams and Theodore Dunham, in 1932, established that it was carbon dioxide. Speculation about the make-up of the clouds continued. In 1937, R. Wildt suggested methanal (formaldehyde), while in 1954, Fred Whipple and Donald Menzel proposed ice crystals. Today, they are known to consist primarily of sulfuric acid.
Hydroxyl radical in Venusian atmosphere
In the May 2008 issue of Astronomy & Astrophysics, Picconi et al. report the first detection of the hydroxyl (-OH) radical in the night-side airglow emission of Venus. The discovery was made using an instrument onboard Venus Express. This is the first detection of -OH in the atmosphere of a planet other than Earth. It is important because it will give new insight into the dynamics of the upper atmosphere and the climate system of Venus.
Venus, life
ashen light
Mars, atmosphere
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• PLANETS AND MOONS
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