Though Venus and Earth appear to be alike in many ways, they are actually very different worlds. There are no oceans and life as we know it could not exist under the tremendous pressures.. On the surface, the atmospheric pressure is 90 times greater than Earth! Venus' air is only 10 times less dense than water, as opposed to Earth's 1000 times less. If you could stand being on the surface of Venus, you could literally strap wings on your arms and fly!
There have been several spacecraft to land on the Venusian surface. Their instruments were only able to survive about an hour, but much data was collected. Images show a rocky world with an orange glow from heavily filtered sunlight through the atmosphere. Soviet landers tested the soil and all the rocks tested were basalts. This confirms the extensive volcanism.
The most common type of terrain on Venus is the gently rolling upland plains which cover about 65% of Venus' surface.
About 20% of Venus is covered by planitia. The planitiae are extremely flat and are comparable to lowland regions.
The highland regions are known as Terra and cover only 10% of Venus. There are only two major highland regions that rise above the lowland regions. They are called Ishtar Terra and Aphrodite Terra. These regions form land masses similar to Earth's continents though much smaller and lower in elevation.
Venus does not have an abundance of craters, and almost no small craters. This can be explained by Venus' atmosphere, which is so thick it would cause most small bodies to burn up on entry. Only larger material would survive to strike the surface. Lava flow from volcanism explains the lack of overall cratering. It is believed that the surface of Venus is only about half a billion years old. Most of the planet has been resurfaced from volcanism. This would mean, of course, that all but the most recent craters have been filled in by lava.
VOLCANISM ON VENUS
Copyright © 1997 Kathy A. Miles and Charles F. Peters II