Thursday, July 30, 2009

Venusian Atmosphere

Chemically, the atmosphere of Venus consists mostly of carbon dioxide (96.5 percent). The remainder is mostly nitrogen. These are organic gases, which might lead one to jump to the conclusion that life—some form of life—may exist on Venus. Indeed, during the 1930s, spectroscopic studies of Venus revealed the temperature of the planet’s upper atmosphere to be about 240 K—close to the earth’s surface temperature of 290 K. Some speculated that the environment of Venus might be a dense jungle.
In the 1950s, radio astronomy was used for the first time to penetrate the dense cloud layer that envelops Venus. It turned out that surface temperatures were not 240 K, but were closer to 600 K. Those temperatures are incompatible with any form of life we know. But the outlook got only worse. Spacecraft probes soon revealed that the dense atmosphere of Venus creates high surface pressure—the crushing equivalent of 90 Earth atmospheres—and that surface temperatures actually top 730 K. And what about those clouds?
On Earth, clouds are composed of water vapor. But Venus shows little sign of water.
Its clouds consist of sulfuric acid droplets.

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