Physical Characteristics of the Planet Venus – Venus is the second closest planet to the Sun after Mercury. This planet orbits the Sun for 224.7 Earth days. Venus has no natural satellites and is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, with an apparent magnitude of −4.6 which is bright enough to cast shadows.
Venus is an inferior planet with an elongation angle of 47.8°. The maximum brightness of this planet can be seen immediately before sunrise or after sunset, so it is called the Morning Star or Evening Star.
Venus is a terrestrial planet and is sometimes called Earth’s “sister planet” because of its similar size, gravity, and composition (Venus is the closest planet to Earth and the planet closest in size to Earth). However, in other respects this planet is very different from Earth.
This planet has the densest atmosphere of the four terrestrial planets consisting of 96% carbon dioxide. Venus’s surface atmospheric pressure is 92 times greater than Earth’s. With an average surface temperature of 735 K (462 °C; 863 °F), Venus is the hottest planet in the Solar System. The planet has no carbon cycle that traps carbon in rocks and surface features, and no organic life that can sequester carbon in the form of biomass.
Venus is shrouded in an opaque layer of highly reflective clouds of sulfuric acid, so its surface cannot be seen from space. Venus may have had oceans, but those oceans are evaporating due to increasing temperatures caused by the continuous greenhouse effect. Much of the water may have been photodissociated, and the solar wind may have allowed free hydrogen to escape into space as a result of the lack of an internal magnetic field on Venus. The surface of Venus itself is deserted, dry, and punctuated by rock that is periodically renewed by volcanic activity.
Physical Characteristics of the Planet Venus
Venus is one of the four terrestrial planets in the Solar System, which means that it is a rocky planet like Earth. Its size and mass are similar to Earth, so this planet is often referred to as Earth’s “sister” or “twin”.
The diameter of Venus is recorded at 12,092 km (only 650 km smaller than Earth) and its mass is approximately 81.5% of Earth’s mass. However, conditions on the surface of Venus are very different from those on Earth, and this is due to Venus’ thick atmosphere which is composed of 96.5% carbon dioxide and 3.5% nitrogen.
The following are the physical characteristics of the planet Venus that distinguish it from other planets.
1. Topography
There has been much speculation about the surface of Venus before it was discovered by space probes in the 20th century. The planet was mapped in detail by Project Magellan in 1990-1991. On the surface there is evidence of volcanic activity, and sulfur in the atmosphere indicates that a volcanic eruption has occurred.
The first physical characteristics of Venus, namely that about 80% of the surface of Venus consists of volcanic land, with 70% is land with wrinkled ridges and 10% is land that is smooth and indented. The remaining 20% are the two upland “continents”; one of the continents is located in the northern hemisphere of Venus, while the other is south of the equator.
The northern continent was called Ishtar Terra, named after Ishtar, the Babylonian goddess of love, and about the size of Australia. The highest mountain on Venus (namely Maxwell Montes) is located on Ishtar Terra. It is approximately 11 km above the average surface elevation of Venus. Meanwhile, the southern continent is nicknamed Aphrodite Terra, after the goddess of love in Greek mythology, and this continent is larger with a size more or less comparable to South America. This continent is filled with a series of faults and faults.
The absence of lava flows in the caldera is still a puzzle. The planet does not have many impact impact craters, indicating that the surface is relatively young, approximately 300–600 million years old. In addition to impact craters, mountains and valleys, Venus also has a unique surface feature. One of them is a volcanic appearance with a flat top, which is called “farra”. They are similar in shape to a pancake and vary in width from 20–50 km, while their height is usually in the 100–1,000 m range.
There are also series of star-shaped radial fractures called “novae”, concentric radial fractures that resemble cobwebs called “arachnoids”, and rings of fractures which are sometimes surrounded by depressions called “coronae”. These features are formed volcanically.
Most of the surface features on Venus are named after women in mythology and history, except for Maxwell Montes which is named after James Clerk Maxwell and the upland regions Alpha Regio, Beta Regio, and Ovda Regio which were named before the current system was adopted by the International Astronomical Union.
The longitudes of surface features on Venus are expressed relative to the prime meridian. The prime meridian initially passes through the bright spot in the center of the Eve feature which is south of the Alpha Region. After Venera’s mission was completed, the prime meridian was determined to pass through the peak in the center of the Ariadne crater.
2. Surface Geology
A second feature of Venus is that most of its surface appears to have been formed through volcanic activity. There are more volcanoes on Venus than Earth, with 167 large volcanoes that can be up to 100 km wide. The only volcanic complex on Earth this size is the Big Island of Hawaii. That doesn’t mean that Venus is more volcanically active than Earth; it is caused by Venus’ older crust.
In comparison, the surface of Venus is estimated to be 300–600 million years old, while on Earth, oceanic crust is continuously recycled through subduction processes at boundaries between tectonic plates, so the average age is around 100 million years. Some evidence points to ongoing volcanic activity on Venus. During the course of the Venera program launched by the Soviet Union, the Venera 11 and Venera 12 probes encountered lightning, and Venera 12 recorded the thunder as it landed.
Venus Express launched by the European Space Agency also found lightning in the atmosphere. While lightning on Earth is caused by rain, there is no rain on the planet Venus (although sulfuric acid descends from the atmosphere, and then evaporates at an altitude of 25 km above the surface). It is possible that the lightning was produced by ash from a volcanic eruption.
Other evidence comes from measurements of sulfur dioxide levels in the atmosphere, which decreased tenfold between 1978 and 1986. This suggests that the initial sulfur dioxide levels were boosted by large volcanic eruptions. Nearly a thousand impact craters are evenly distributed across the surface of Venus. On other cratered celestial bodies, such as the Earth and Moon, the craters appear to be degraded. On the Moon, degradation is caused by subsequent impacts, while on Earth the process is driven by erosion by wind and rain. On Venus, 85% of craters are still in an undegraded state.
The number of craters and their undegraded state indicate that the planet underwent a global resurfacing event approximately 300–600 million years ago, which was followed by reduced volcanism. While the Earth’s crust is constantly moving, Venus’ crust is thought to be unable to support this process.
Without the existence of plate tectonics to reduce the temperature of the mantle, Venus experienced a cyclical process that caused the temperature of the mantle to increase, eventually weakening the crust. Then, over about 100 million years, large-scale subduction occurred which recycled Venus’ crust.
The diameter of the craters on Venus varies from 3 km to 280 km. There are no craters smaller than 3 km in diameter due to the effect the dense atmosphere has on foreign bodies entering Venus. Objects with a kinetic energy less than a certain number will be slowed down by the atmosphere so they don’t produce an impact crater. Objects smaller than 50 meters in diameter will break up and burn up in the atmosphere before reaching the surface.
3. Deep Structure
Without seismic data or data regarding the moment of inertia, little is known about Venus’ internal structure and geochemistry. The similarity in size and density of Venus to Earth suggests that they may have a similar internal structure consisting of a core, mantle and crust. Like Earth, Venus’ core is partially molten because the two planets are cooling at the same rate.
Venus’ slightly smaller size means that the pressure inside Venus is much lower than on Earth. However, the main physical difference between the two planets is the absence of plate tectonics on Venus, which is probably due to Venus’ crust being too strong without the presence of water to reduce its viscosity.
As a result, the amount of heat lost on Venus is lower, thereby inhibiting planetary cooling and possibly explaining why Venus has no internal magnetic field. Venus may instead be losing its internal heat in the process of periodic resurfacing.
4. Atmosphere and Climate
The next physical characteristics of Venus, which has a very dense atmosphere, which consists of 96.5% carbon dioxide and 3.5% nitrogen. The mass of its atmosphere is 93 times greater than that of Earth’s, while the pressure on the surface of the planet Venus is 92 times greater than on the surface of the Earth—a pressure roughly comparable to that of an ocean 1 kilometer deep on Earth.
The density on the surface of Venus is recorded at 65 kg/m³ or 6.5% of the density of water. The CO2-rich atmosphere and thick sulfur dioxide clouds produce the most intense greenhouse effect in the Solar System, resulting in an average surface temperature of Venus of 462 °C (864 °F). As a result, the surface of Venus is hotter than that of Mercury, which has a minimum surface temperature of −220 °C (−364.0 °F) and a maximum surface temperature of 420 °C (788 °F), even though Venus is farther from the Sun and as a result only gains 25% of the irradiance that Mercury receives. The surface of Venus is often described as hellish. The temperature on Venus is also higher than the temperature for sterilization.
Research suggests that billions of years ago, Venus’ atmosphere was much closer to Earth’s than it is today, and there may have been water on the surface. However, over a period of 600 million to several billion years, a sustained greenhouse effect is caused by the evaporation of water which creates greenhouse gases in the atmosphere. Although the surface of Venus cannot support life the way it does on Earth, the possibility of habitable niches in the lower and middle early layers cannot be discounted.
Thermal inertia and heat transfer by winds in the lower atmosphere mean that the surface temperature of Venus does not vary much between the light and dark sides, even though the planet’s rotation is very slow. Surface winds are slow at a few kilometers per hour. However, due to the high atmospheric density on the surface of Venus, these winds are quite significant and are able to move dust and small rocks on the surface. In addition, the wind can also make it difficult for pedestrians even if heat, pressure, and lack of oxygen are not a problem.
Above the CO2 layer are thick clouds consisting of sulfur dioxide and sulfuric acid. The precipitate reflects and scatters about 90% of the sun’s light, hindering observations of Venus’ surface. As a result of this permanent initial layer, even though Venus is much closer to the Sun than Earth, its surface is not as bright as Earth’s.
Winds as high as 300 km/h (190 mph) over the clouds circle Venus every four to five earth days. The wind speed of Venus is 60 times faster than the rotation of Venus, while the speed of the fastest winds on Earth is only 10–20% of the speed of Earth’s rotation.
The surface of Venus is isothermal; the planet has a constant temperature not only between day and night, but also between the equator and the poles. Venus’ axis tilt of less than 3° also minimizes seasonal temperature variations.
The only appreciable temperature variation is due to altitude. In 1995, the Magellan probe managed to image a highly reflective substance on the top of the tallest mountain that looks a lot like snow on Earth. This substance was likely formed by the same processes as snow, albeit at a much higher temperature. This snow is too volatile on the surface, so it rises to colder elevations in a gaseous form, and then precipitates. The identity of this substance is still not known with certainty, but there are various speculations such as tellurium and lead sulfide (galena).
Venus’ clouds are capable of producing lightning like clouds on Earth. The existence of lightning has been controversial since its first discovery by the Venera spacecraft. In 2006-2007, Venus Express discovered electromagnetic electron waves, which are signs of lightning. Their intermittent occurrence suggests patterns related to weather activity.
In 2007, the Venus Express probe discovered an atmospheric vortex at Venus’ south pole. In addition, in 2011, this spacecraft also managed to find the ozone layer in the upper atmosphere of Venus. Furthermore, on January 29, 2013 scientists from the European Space Agency reported that the ionosphere on the planet Venus appears to have a tail like the ions that follow from a comet.
5. Magnetic Field and Core
The final physical characteristics of Venus, namely its magnetic field is weaker than that of Earth. In 1967, Venera 4 discovered that this magnetic field results from interactions between the ionosphere and the solar wind, and not from a dynamo in the core as it does on Earth. Venus’ magnetosphere provides protection from insignificant cosmic radiation. The radiation may produce cloud-to-cloud lightning.
The absence of an internal magnetic field on Venus is surprising because Venus was once thought to have a dynamo as a result of its size being not much different from Earth. Dynamo requires three things, namely conductive liquid, rotation, and convection. Venus’ core is thought to be electrically conductive. In addition, even though it is considered too slow, according to simulations of Venus’ rotation it can still produce a dynamo.
The absence of a dynamo on Venus is due to the absence of convection in the Venusian core. On Earth, convection takes place in the liquid outer layers of the core because the bottom is much hotter than the outside. On Venus, global resurfacing events may have halted plate tectonics and consequently reduced heat flux in the crust. As a result, the temperature of the mantle increases, thereby reducing the heat flux from the core. This is why there is no internal geodynamo capable of generating a magnetic field, instead the thermal energy from the core is used to reheat the crust.
Another possibility is that there is no solid core on Venus, or that the Venusian core is not currently cooling, so that all of the liquid portion exists at roughly the same temperature. It’s also possible that Venus’ core has completely solidified. The shape of Venus’ core is highly dependent on the concentration of sulfur, which is currently unknown.
Due to the weak magnetosphere, the solar wind interacts directly with Venus’ outer atmosphere, which produces hydrogen and oxygen ions by dissociating neutral molecules from ultraviolet radiation. Energy from the solar wind then causes some of the ions to experience release from Venus’ gravitational field.
As a result of this erosion process, low mass hydrogen, helium and oxygen ions are released, while high mass molecules such as carbon dioxide are more able to survive. Atmospheric erosion may also have contributed to the loss of water during the first billion after formation. In addition, erosion increases the ratio of high-mass deuterium to low-mass hydrogen (D/H ratio) in the upper atmosphere.
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Those are the 5 characteristics of Venus that you can learn. It was concluded that the hottest planet in the solar system is Planet Venus.