Venus is the second closest planet to the Sun and our nearest planetary neighbour. With a diameter of 12104 kilometres it is the closest in size to the Earth. Its orbit about the Sun takes 224.7 days with its distance from the Sun being almost three-quarters that of the Earth. The planet rotates retrogradely in 243 days with respect to the stars (117 days with respect to the Sun, the Venusian day). From the Earth the planet's surface is never seen as it is always covered by very dense layers of clouds. The upper clouds rotate with a period of four days at speeds of 350 km/hr. Because the size and mass of Venus are close to those of the Earth it was supposed by many that Venus might be Earth like and might even have life-forms on its surface. The truth is that Venus is very different from the Earth and it is extremely unlikely that there is any possibility that life has formed on Venus. Venus was the first planet to be explored. The Mariner 2 spacecraft, launched on August 27, 1962, was the first of more than a dozen successful American and Soviet missions to study the mysterious planet. As spacecraft flew by or orbited Venus, plunged into the atmosphere and gently landed on Venus' surface, romantic myths and speculations about our neighbour were finally laid to rest.
Venus is covered with clouds made of sulphuric acid which obscure our view of the surface. They are not composed of water droplets, as on the Earth, but are believed to be composed of droplets of sulphuric acid and particles of sulphur! Thus making Venus a very unpleasant place for man to contemplate visiting! The surface of Venus can only be seen by space probes which have parachuted down through the atmosphere to the surface. These can not survive the hostile environment for long but have given us glimpses of a stony terrain with no great weathering and no great range of heights. The surface of Venus is mostly covered by volcanic materials. Volcanic surface features, such as vast lava plains, fields of small lava domes, and large shield volcanoes are common. There are few impact craters, suggesting that the surface is, in general, geologically young - less than 800 million years old.
Venus has no natural satellites.
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