VENUS: THE SISTER PLANET

Because Venus is rather resembling in size and mass to Earth, it is often called Earth's twin. Some even refer to Venus as the "Sister Planet". Eventhough they are extremely different from one another in several manners, some scientists believe that studying Eart will increase their understanding of our planet.

Venus' revolves around the sun once every 224.7 Earth days. Its orbit is the most circular of all the planets in the solar system. It rotates on its axis very slowly, and it takes 243 Earth days to rotate once. In other words, 243 Earth days is equal to one day on Earth. Its direction of rotation if from left to right which is opposite to the rotation of the majority of the other planets. Since the north pole of planet is determined by the direction of its rotation, Venus' north pole is, in reality, where its south pole would be on any other planet, and the tilt of its axis is 177 degrees. Venus is probably the only almost completely upside down planet.

Through the lens of a telescope, Venus looks like a sparkling white disk, because it is always covered by a dense, thick layer of shining white clouds. They are made of carbon diioxide and small droplets of sullfuric acid, which was discovered by the first space probe that flew there. That same space probe also discovered that the clouds end aproximatellly 30 miles (48 kilometers) above the surface and that powerful wind blow these cloud layers around Venus. They circle the planet in about four Earth days at a speed of about 225 miles (L362 kilometers) per hour. That is why Venus seems to rotate in four Earth days, the speed of the clouds.

Venus has an atmosphere of almost 97 percent carbon dioxide, 3 percent nitrogen, and tiny amounts of wxygen, carbon monoxide, argon, and sulfuric dioxide. Its atmosphere becomes thicker close to the surface, where the temperature is aproximately 900 degrees Farenheit (480 degrees Celcius).

Radar images sent from space probes have shown that Venus' surface is dry and desertlike. Over 60 percent of its surface is made up of immense, low-lying plains covered by flowing volcanic lava.

Two mountainous areas, Ishtar Terra and Aphrodite Terra, rise higher than the plains and ar similar to continents. Aphrodite Terra is similar to Africa in size, and Ishtar Terra is as large as Australia. There is also a grand plateau named Lada Terra. Venus also contains many vast volcanic regions covered with hundreds of volcanoes over 12 mmiles (19 kiloometers) in diameter and tens of thousands of smaller volcanoes. The largest of these volcanic areas is Beta Regio. Some smaller regions are Phoebe Regio, Themis Regio, and Alpha Regio. The biggest volcano on Venus, Maxwell Montes, is located within Ishtar Terra. Its summit is located about 12 miles (19 kilometers) higher than the average elevation on Venus. The summit of Maat Mons, another immense volcano, has erupted within the last 10 million years. It is the youngest large volcano on Venus. Sulfuric dioxide is released into the air as the volcanoes erupt. It then reacts with the other elements, and sulfuric acid is the result.

Within the volcanid areas on Venus lie circular valleys. Artemis Chasma, the vastest of these, is aproximately 1,100 miles (1,800 kilometers) in diameter. It is thought by geologists that these valleys could be places where magma, or molten material, at one time swelled the ground, withdrew, and left large round wrinkles in its surface. Networks of spiderlike cracks outwardly extend from the valleys. They might have resulted from the same cycle of volcanic activity. Its surface is also lined with big lava channels.

Venus' surface only has a few hundred meteor craters which geologists believe suggests that its surface is somewhat new. In a search below the layers of lava, older meteor craters might be found from volcanoes that were active 500 million years ago.

Venus remained a mystery for many years, because the dense layers of clouds covering the planet hid its secrets. Many of those secrets have been revealed by the several space probes, especially those that landed on Venus. Scientists anticipate explorations in the future to uncover even more.

This page is written by LESLIE M. BAILEY in the astronomy class of BCC/Broward County on July 1998