General Information

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 (215 mph). 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 can be very easily seen from the Earth. It is often called the Evening or Morning star and is often the brightest object visible in the sky, with the exception of the Sun and Moon. Because its orbit lies inside that of the Earth, Venus appears to move out from the Sun to a maximum distance, called greatest elongation, and then back towards the Sun. After passing behind, or in front of, the Sun it moves away from the Sun on the opposite side. The times when Venus is behind or in front of the Sun are called inferior and superior conjunctions. If the orbits of the Earth and Venus were in the same plane then at each conjunction Venus would either pass directly behind or in front of the Sun, but because the orbits are inclined to one another, we see Venus pass in front of the Sun's disc, called a transit, only rarely. The next such transit will occur in 2004. Through a small telescope Venus can be easily seen to have phases, like the Moon.