Introduction

Venus is second planet out from our sun and the closest planet to Earth. Beginning in 1961 the United States and former Soviet Union have depolyed a long string of space probes that have examined the Venusian atmosphere and peered beneath its dense cloud cover. The probes have revealed that Venus is an extremely hot, dry planet, with no signs of life. Its atmosphere is made primarily of carbon dioxide with some nitrogen and trace amounts of water vapour, acids, and heavy metals. Its clouds are laced with sulfur dioxide.

What is the cause of the tremendous heat on Venus?

Venus provides a perfect example of the greenhouse effect. Heat from the sun penetrates the planet's atmosphere and reaches the surface. The heat is then prevented from escaped back into space by atmospheric carbon dioxide. The result is that Venus's surface temperature is a fierce 900 degrees (482 degrees Celsius), even hotter than that of Mercury, its neighbour closer to the sun.

How does Venus rotate?

Venus is unusual in that it is the only planet besides Uranus to rotate from east to west. Thus, if you lived on Venus, the sun would rise in the west and set in the east. In addition, Venus rotates very, very, slowly. In fact, it takes Venus 243 Earth days to complete one rotation. A day on Venus lasts even longer than its year (length of time it takes Venus to orbit Venus to orbit the sun), which is 255 Earth days.

What are the surface features of Venus like?

U.S and Soviet space probes studying Venus uncovered a rocky surface covered with volcanes (some still active), volcanic features (such as lava plains), channels (like dry riverbeds), mountains, and medium and large craters. No small craters exist, apparently because small meteorites cannot penetrate the planet's atmosphere. Another set of features found on the surface are arachnoids. These features are circular formations ranging anywhere from 30 to 137 miles (48 to 220 kilometers) in diameter, filled with concentric circles extending spokes outward.

How old is Venus's surface?

The most recent probe to study Venus, Magellan, mapped the entire Venusian surface from 1990 to 1994. It discovered that, from a geological viewpoint, the planet's surface is relatively young. Astronomers analyzing Magellan's data have concluded that about three hundred to five hundred years ago, lava erupted and covered the entire plane, giving it a fresh, new face. One indication of this event is the presence of craters and other formations on the surface that lack the same weathered appearance of that of older formations. Also, relatively few craters appear on Venus. In fact, more craters can be counted when viewing a section of the moon through a small telescope than occur on the entire surface of Venus.

What are the plans for the future exploration of Venus?

The Amercian space probe Magellan collected enough information on Venus to keep scientists busy with analysis for years to come. Even so, discussions are now taking place about the possibility of sending a joint U.S.-Russian space-probe laboratory back to Venus to learn more.

Can I see Venus from Earth?

Venus is visible in the sky either just after dark or just before sunrise, depending on the season. This pattern prompted ancient astronomers to refer to the planet as the "evening star" or "morning star". Venus, named for Roman goddess of love and beauty, has been thought of throughout history as one of the most beautiful objects in the sky. It is often referred to as a brightly glittering jewel.

Why are Earth and Venus called sister planets?
Venus and Earth have long been considered sister planets. The reason for this comparsion is that they are similar in size, mass and age. And while astronomers could not see beneath Venus' thick cloud cover until recently, they assumed that Venus would have seas and plant life like that on Earth. We now know, however that this is not the case. The two planets are so different that it hardly makes sense to still call them "sister".

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