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Space Venus :: Surface Features of Venus
Surface Features of Venus
Instead of west to east rotation as most of the major planets do, Venus has slow retrograde rotation, means that it rotates from east to west (Pluto and Uranus also have retrograde rotation, though Uranus's axis, tilted at 97.86 degrees, almost lies in its orbital plane.) It is not known why Venus is dissimilar in this manner, even though it may be the result of a collision with a very large asteroid at some time in the distant past. If the Sun could be seen from Venus' surface, it would appear to rise and set in a 116.75 day cycle (Venus' synodic rotation period), and a Venusian year would thus last 1.92 Venusian "days".
Venus has two major continent-like highlands on its surface, mounting over vast plains. The northern highland is named Ishtar Terra and has Venus's highest mountains, named the Maxwell Montes (roughly 2 km taller than Mount Everest) after James Clerk Maxwell, which surround the plateau Lakshmi Planum. Ishtar Terra is about the size of Australia. In the southern hemisphere is the larger Aphrodite Terra, about the size of South America. Between these highlands are a number of broad depressions, including Atalanta Planitia, Guinevere Planitia, and Lavinia Planitia.
With only the exemption of Maxwell Montes, all surface features on Venus are named after real or mythological females. Venus' chunky atmosphere causes meteors to decelerate as they fall toward the surface, and even large meteors will strike the surface at too low a speed to form a collision crater if they have less than a certain threshold kinetic energy. Because of this, no impact crater smaller than about 3 km (2 mi) in diameter can form.
Venus's intrinsic magnetic field has been found very feeble compared to other planets in the solar system. This may be due to its slow rotation which is not enough to make an internal dynamo of liquid iron. As a result, solar wind strikes Venus's upper atmosphere without intervention.
It is notion that Venus originally had as much water as Earth, but that under the Sun's physical attack water vapor in the upper atmosphere was split into hydrogen and oxygen, with the hydrogen escaping into space owing to its low molecular mass; the ratio of hydrogen to deuterium (a heavier isotope of hydrogen which doesn't escape as quickly) in Venus's atmosphere seems to sustain this theory. Molecular oxygen is thought to have combined with atoms in the crust (large amounts of oxygen, however, remain in the atmosphere in the form of carbon dioxide). Because of their dryness, Venus's rocks are much harder than Earth's, which leads to steeper mountains, cliffs and other features.
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Physical Characteristics of Venus
Observations And Explorations Of Venus
Historical Observations of Venus
Phases Of Venus
Early Flybys of Venus
Early Landings of Venus
Venus Early Orbiters
Further Soviet Successes
Venus Vega Lander
Venus Recent Flybys