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hor_green_bar1.jpg Resemblance to Earth hor_green_bar1.jpg


Venus - copyright Calvin J. HamiltonVenus is often regarded as the Earth's sister planet, sharing many similar characteristics such as size, mass, and chemical composition. Venus is only a little smaller, having a diameter 95% of Earth and 80% of Earth's mass. The densities and volumes are also very much alike. Historically, these two planets condensed from the same nebula around the same time.

Ultraviolet view of Venus' atmosphere - courtesy NASAIn recent times, scientists have found that despite these similarities, Venus and Earth are radically different. The atmosphere of Venus is composed of thick clouds of sulfuric acid and large quantities of carbon dioxide. The atmospheric pressure of Venus is very great, being 92 times that of Earth's atmospheric pressure at sea level. That is equivalent to diving 1 kilometer into the ocean. In addition, the thick atmosphere also burns up any small meteorite entering the planet. Thus the craters on Venus are usually very large and never smaller than 2 kilometers in diameter.

There are also ery strong winds on the highest altitudes of Venus' clouds. Some reach a speed of 250 kilometers and hour while near the surface, winds only drift along at several kilometers an hour.



Hemispheric view of Venus - courtesy NASAVenus also has an extremely high surface temperature, often reaching a searing 482º C (900º F) due to a runaway greenhouse effect. This is caused by Venus' thick canopy of carbon dioxide that traps external solar energy when it is radiated from the planet's surface. Therefore, Venus has a higher surface temperature than Mercury, even though it is further from the Sun.

Because of the high surface temperatures, Venus has no water in any form anywhere on the surface of the planet. Although water may have once been abundant on the surface, its closeness to the un and the greenhouse effect boiled it all away.




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