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| Quick Facts
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Orbital Distance: 0.72 Earthıs orbit
Orbital Period: 0.62 Earth years
Rotation: 243 Earth days (retrograde)
Mean Radius: 0.95 Earthıs radius
Mass : 0.815 Earth's mass
Surface Pressure : 90 atmospheres
Gravity : 0.91 Earthıs gravity
Orbit : 108,200,000 km (0.72 AU) from Sun
Diameter : 12,103.6 km
Mass : 4.869 x 10^24 kg
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| Introduction to Venus
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Venus is the second closest planet to the Sun. It has no moon. With a diameter of 12104 kilometres, it is the closest in size to the Earth. Its orbit about the Sun takes 224.7 days with its mean distance from the Sun being almost three-quarters that of the Earth. Venus is the only planet that rotates retrogradely (which means that it rotates in a clockwise direction) in 243 days with respect to the stars (117 days with respect to the Sun, the Venusian day). A Venusian day is even longer than its year! From the Earth, the planet's surface is never seen as it is always covered by very dense layers of clouds.
Venus is always known to people as the twin planet of our mother earth. Venus is only slightly smaller than Earth (95% of Earth's diameter, 80% of Earth's mass). Both have few craters indicating relatively young surfaces. Their densities and chemical compositions are similar.
Nevertheless, Conditions on these two planets were very much different. Scientist first thought that the thick continuous cloud cover of the Venus atmosphere is a good sign as it suggested moisture is present in large amount. Just like on earth, where every living organism depended on water for life, Venus was assumed that it could support life with all the water it had. Scientist often wondered if there was a vibrant Venusian world behind the thick cloud cover, overflowing with life.
However, the dreamland of Venus was soon dashed, as spacecrafts that visited the place have revealed that the real condition on Venus was the exact opposite. The thick clouds were not made up of water vapor, instead is sulphuric acid which is used mainly for car batteries. Composition of air was dominated by the overwhelming amount of carbon dioxide present. The carbon dioxide results in greenhouse effects and rises the global temperature of Venus to about 450 degree Celsius.
Beautiful as its name was Venus was named after the goddess of beauty and love, it is considered the most spectacular planet apparent to naked eye from earth. It is often called the morning or evening star (also known as: Eosphorus as the morning star; Hesperus as the evening star as it was popularly thought to be two separate bodies), as it often appears fairly low in the east-southeast at sunrise and west-northwest at sunset. Its brilliance can be explained in four ways:
1) First, it's close to the Sun, so intense sunlight strikes it.
2) Second, it's fairly large about the size of Earth.
3) Third, Venus has clouds that reflect most of the sunlight.
4) Fourth, Venus comes closer to Earth than any other planet does.
As Venusıs orbit is inside that of our earthıs own, Venus will show phases like the moon. The shape of Venus remains in a crescent shape. It is never full, as Venus will never move beyond the earthıs orbit.
| Surface of Venus
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The most modern information about the surface comes from the Magellan Venus orbiter. This uses radar to map the surface. The interior of Venus is believed to be similar to that of the Earth with a metallic core and silicate mantle. Unlike the Earth, Venus has a very small magnetic field apart from that induced by the effect of the solar wind.
Most of Venus' surface consists of gently rolling plains with little relief. There are also several broad depressions: Atalanta Planitia, Guinevere Planitia, Lavinia Planitia. There two large highland areas: Ishtar Terra in the northern hemisphere (about the size of Australia) and Aphrodite Terra along the equator (about the size of South America). The interior of Ishtar consists mainly of a high plateau, Lakshmi Planum, which is surrounded by the highest mountains on Venus including the enormous Maxwell Montes.
The active volcano, Maat Mons, discovered on Venus by the Magellan spacecraft. Data from Magellanıs imaging radar shows that much of the surface of Venus is covered by lava flows. There are several large shield volcanoes (similar to Hawaii or Olympus Mons) such as Sif Mons. Recently announced findings indicate that Venus is still volcanically active, but only in a few hot spots; for the most part it has been geologically rather quiet for the past few hundred million years.
Active volcanoes are known to exist on only two planets in the solar system, Venus and the Earth. Extinct volcanoes are seen on Mars. Two satellites are known to have active volcanoes but these are very different from those on the Earth and on Venus. On Io, moon of Jupiter, there are active sulphur volcanoes and on Triton, a moon of Neptune there are active volcanoes whose temperatures are far below zero centigrade.
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