Venus, the jewel of the sky, was named after the Roman goddess of love and beauty. Astronomers refer to Venus as Earth’s sister planet. Both planets are similar in size, mass, density, composition and gravity. These were the similarities. But unlike Earth, Venus has no oceans and is covered by a thick, rapidly spinning atmosphere composed primarily of carbon dioxide with almost no water vapor. The clouds at Venus are composed of sulfuric acid droplets. This thick atmosphere creates a scorched world with temperatures hot enough to melt lead and the atmospheric pressure which is 92 times that of the Earth’s at sea-level.
Temperature on Venus
Venus is baked with a surface temperature of about 482° C (900° F). This high temperature is mainly due to a runaway greenhouse effect caused by the heavy atmosphere of carbon dioxide. Sunlight passes through the atmosphere, this way heat is radiated in and is trapped by the dense atmosphere and is not allowed to escape into space. Because of the green house effect planet Venus is hotter than Mercury.
Venus Atmosphere
The atmosphere of Venus consists primarily of carbon dioxide, with clouds of sulfuric acid droplets. Some trace amounts of water have also been discovered in the atmosphere. This thick atmosphere traps the Sun’s heat and hence results in very high surface temperatures. Sulfur compounds are plentiful in Venus’ clouds. The corrosive chemistry and dense moving atmosphere results in significant surface weathering and erosion.#1
Transits of Venus
Just like Mercury, Venus can be seen periodically passing across the face of the Sun. These “transits” of Venus take place in pairs with over a century separating each pair. As Venus’s orbit is significantly larger than Mercury’s orbit, transits of Venus are much rarer. In fact, only six such events have taken place ever since the invention of the telescope (1631,1639, 1761,1769, 1874 and 1882). Transits of Venus are only probable during early December and June when Venus’s orbital nodes pass across the Sun. Transits of Venus show a clear pattern of recurrence at intervals of 8, 121.5, 8 and 105.5 years.
Venus is Dry
The Earth has a shielding layer known as the Ozone Layer to prevent us from Sun’s ultraviolet rays. Venus does not have an ozone layer to block the ultraviolet radiation from the Sun. Therefore UV rays find its way directly into Venus’ atmosphere. For over many billions of years this radiation has gradually broken down water molecules into hydrogen and oxygen. Therefore, there is now very little water left on Venus.
From West to East
The year or orbital period on Venus is almost 225 Earth days long, whereas the planet’s rotation period is 243 Earth days, making a Venus day about 117 Earth days long. In addition to this the Planet Venus rotates in the opposite direction as almost all the other planets. Because of this instead of the Sun rising in the east and setting in the west, the Sun on Venus would appear to rise in the west and set in the east.
As Venus moves ahead in its solar orbit and slowly rotating “backwards” on its axis, the top level of cloud layers zooms around the planet every four Earth days, driven by hurricane-force winds which travel at about 360 kilometers per hour. The wind speeds in the clouds reduce with cloud height, and winds at the surface are likely to be just a few kilometers per hour. Scientists are still investigating how this atmospheric “super-rotation” forms and how it is maintained.
Visibility of Venus
Venus appears to be the brightest planet in the sky because of its proximity to Earth and the way its clouds reflect sunlight. Even though we cannot generally see through Venus’ thick atmosphere, NASA’s Magellan mission to Venus in the early 1990s used radar to image 98 percent of the surface, and the Galileo spacecraft used infrared mapping to observe mid-level cloud structure as it passed by Venus in 1990 on the way to Jupiter. Four of the most successful missions in enlightening the Venusian surface are NASA’s Pioneer Venus mission (1978), the Soviet Union’s Venera 15 and 16 missions (1983-1984), and NASA’s Magellan radar mapping mission (1990-1994).
Topography of Venus
Geologically speaking the surface of Planet Venus is relatively young. It appears to have been fully resurfaced 300 to 500 million years ago. Scientists are researching on how and why this happened. The topography of Venus consists of vast plains which are covered by lava flows and mountain or highland regions deformed by geological activity. Venus has a small number of mountainous areas along with widespread flat areas. There are craters and proof that the surface long ago moved, much like the surface of the Earth moves at present. However unlike the Earth’s surface, there is no proof that Venus has a tectonic plate system.
Venus has many volcanoes. However unlike the volcanoes on Earth which can at times explode in an explosive manner, the volcanoes on Venus are supposed to explode in a less violent way. In reality, it is supposed that they don’t explode at all, but it is thought that the lava just slowly flows out onto the surface.#2
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[image] – www.nasa.org
