Venus

Aphrodite to the Greeks and Venus to the Romans, the Goddess of Love. Today, Venus is still a sight of natural beuty and the brightest solar body visible from Earth except for the Sun and Moon. Venus is 108 million km from the Sun (0.72AU) and is the second of the terrestrial planets. It has a diameter of 12,104 kilometers and is almost exactly the same size of Earth, and has a solid surphace and an atmosphere. Beyond that, however, the two planets are completely different. The Venusian atmosphere contains a thick cloud cover which covers 100% of the surface of Venus, all the time. This means that the surface of Venus is not detectable from Earth, and that direct sunlight never penetrates the clouds. Though 17th and 18th century astronomers were unaware of this, they tried to 'map' Venus. The 100% cloud cover was confirmed in the 20th century.

The atmosphere of Venus is composed mainly of carbon dioxide (96%). The clouds contain water vapour and sulfur dioxide, and squalls of acid rain fall on Venus. Massive electrical storms are also common, and their lightning, observed from Earth as 'ashen light', once was thought to be lights from Venusian cities.

Since 1962, when the American Mariner 2 spacecraft flew near Venus, a dozen unmanned planetary probes have been launched from both the U.S.A and Russia (formerly the Soviet Union), and have begun to unlock the many secrets of Venus. In 1978, when the American Pioneer venus spacecraft used radar to 'look' beneath the clouds, the nature of Venus' surface features were revealed. The picture painted by the returned data was that of a barren rock, at a temperature of 482 degrees C. People had thought that there might be lush forests beneath Venus' clouds, benifiting from the abundance of carbon dioxide. But the temperature was far too hot for water to exist in liquid form. The US spacecraft Magellan is the most recent proba and has produced detailed maps of Venus' surface using radar.

Venus' atmospheric pressure is 100 times greater than that of Earth's. This means that it has been very difficult to conduct sucessful spacecraft landings. Four Soviet Venera spacecraft have landed on the surface, but could only get two pictures apeice before being crushed. Becuase of the Pioneer Venus project of 1978 and the Magellan project in 1989, we do have a vague idea of what Venus looks like. In the northern hemisphere there is a vast upland region, which has been dubbed Ishtar Terra. The highest point is the Maxwell Mountains, that rise to 35,00 ft. There is also a great upland area in the southern hemisphere called Aphrodite Terra, which measures 11,200km, across. It also contains Venus' deepest canyon, the Diana Chasme, whose floor is 9500 ft below the mean radius of the planet.

A Venusian day consists of 243 Earth days, and it's year is 225 Earth days, which means it takes longer to rotate 360 degrees than it does for it to orbit the Sun once. Venus' orbit is retrograde. In addition, the periods of Vens' rotation and of its orbit are synchronized such that it always presents the same face toward Earth when the two planets are at their closest approach.

Venus probably had large amounts of water like Earth, but has been boiled away. The surface of Venus is covered with lava flows. There are several large sheild volcanoes and recently announced findings indicate Venus is still volcanicly active.

Venus has an iron core of about 600km in diameter, a molten rocky mantle compromising the majority of the planet and a crust which is a lot stronger and thicker than anyone predicted. Venus doesn't have a magnetic feild.