|
|
|
VENUS
Venus is the second closest planet to our Sun at 67 million miles. It revolves around the Sun every 225 days, but its rotation takes 243 days. Therefore, the planet's day is slightly longer than the length of its year. One other interesting note is that Venus rotates clockwise, the only planet in our solar system to do so, and contrary to its own orbit around the Sun. New research suggests that the "backward" rotation is caused by tides which are raised in the thick atmosphere by the Sun, and with friction interaction between the atmosphere and planet itself. It is hypothesized that these interactions caused Venus's rotation to slow, stop, and then reverse. This is somewhat similar to what is happening here on Earth, as our Moon's pull on our oceans causes tides whose subsequent friction is gradually slowing Earth's rotation.
Atmosphere and Weather: Venus has a thick atmosphere made up almost entirely of carbon dioxide. It also exerts a pressure 100 times higher than the earth's, resulting in a pressure-cooker environment. Venus is covered by dense clouds made up of sulfuric acid and water vapor. The clouds are so thick, that it is impossible to see its surface without using sophisticated radar systems. The surface is desolate, complete with a low number of large craters, volcanic rock, and lava flows. Continent like features exist, including canyons, sand dunes, mountains and waterless oceans.
The incident visible and infrared spectrum from the Sun are major contributors to the extremely hot temperatures on Venus, with the dense, carbon dioxide atmosphere not letting the infrared rays escape back into space. These temperatures resemble something more of a raging fire due to an uncontrolled greenhouse effect which more than doubles the temperature on the planet's surface. It appears that the surface temperature ranges from about 820 degrees to nearly 900 degrees F. The average surface temperature is 847 degrees F., hot enough to melt lead. No wonder the ocean basins are "dry". At these temperatures any water would evaporate nearly instantaneously. Previous probes from the Pioneer Spacecraft in December 1978 revealed very high winds aloft in its atmosphere, approaching speeds of 200 mph. This could explain why the night side of the planet has temperatures nearly the same as the day side, as the strong winds aloft transfer heat around the globe. However it appears that the surface winds are very light.
In short, Venus is by far the hottest planet in our solar system, with a very minimal diurnal temperature spread. It is also the third brightest object in the sky, next to the Sun and Moon.
|
|
Because the surface of Venus is obscured by thick clouds in its atmosphere, it reflects light very strongly. The Magellan space craft managed to map the surface of Venus. This revealed 1600 major volcanos, mountains, large highland terrains, and vast lava plains.
More than 1,000 volcanoes or volcanic centers larger than 20 km in diameter dot the surface of Venus. There may be close to a million volcanic centers that are over 1 km in diameter. Much of the surface is covered by vast lava flows. In the north, an elevated region named Ishtar Terra is a lava-filled basin larger than the continental United States. Near the equator, the Aphrodite Terra highlands, more than half the size of Africa, extend for almost 10,000 km. Volcanic flows have also produced long, sinuous chan-nels extending for hundreds of kilometers.
|
|
The atmosphere on Venus is very thick, at 90 times heavier than Earth's. This is the equivalent pressure a submarine experiences at 3000 feet below sea level. Because the atmosphere is composed mostly of carbon dioxide, a greenhouse gas, the temperatures on Venus are extremely high. This results in temperatures of about 460°C, or 860°F. The surface of Venus experiences acid rain, due to the clouds of sulfuric acid clouds.
Other atmospheric gases include nitrogen, and traces of carbon monoxide, argon, sulfur dioxide, and water vapor.
|
|
The core of Venus is thought to be similar to Earth's - with a rocky mantle, molten core and a crust.
|
|
The exact date of Venus' discovery is not knows, due to the fact that it is so obvious in the sky. However, during the 1950s, astronomer Robert Richardson noticed that Venus rotates "backwards". This means that it rotates in the opposite way than Earth, and most of the other planets.
|
|
|
Planet
|
Diameter: 12,104 km (7,522 miles)
Mass: 4.87x10^24 kilograms
Density: 5,243 kg/m^3
Minimum Distance from Sun: 108 million km
Maximum Distance from Sun: 109 million km
Minimum Distance from Earth: 40 million km
Name in Roman/Greek Mythology: Venus/Aphroditie
Rotation Period around Axis: 243 days (retrograde)
Revolution Period: 0.62 years
Tilt of Axis: 177-178°
Surface Gravity: 8.87 m/s^2
Temperature Range: 457° C (855° F)
Average Surface Temperature: 730K
|
|
