Venus
Named after the Roman goddess of love and beauty, Venus may appear beautiful on the outside, but there is a deadly and hellish landscape within.
Earth’s “Twin”
Venus comes second in the line of planets and is the closest neighbor to Earth. Venus is often called Earth’s twin because of their similar size and density, but I like to think of Venus as the evil twin. Venus may be the same size, but it’s a lot scarier. Unlike Earth, Venus’ atmosphere is thick and toxic, filled with carbon dioxide and sulfuric acid. This takes the greenhouse effect (gases in atmosphere trap heat) to a new level, causing temperatures on Venus to rise to about 900 degrees Fahrenheit or 475 degrees Celsius. This is hot enough to melt lead or cook a 16-inch pepperoni pizza in just seven seconds. The heavy atmosphere causes a deadly pressure of more than 90 times that of Earth’s. Naming Venus after the goddess of love and beauty may not have been the right move. Venus also rotates clockwise, unlike all other planets, making the Sun rise in the west and set in the east.
Venus Stats
Equator circumference: 38,025km
Radius: 6,052km
Average distance from Sun: 108 million km
Surface temperature: 462°C
Average orbital speed: 126,074km/h (35km/s)
Sidereal day length: 243 Earth days
Solar day length: 117 Earth days
Year length: 225 Earth days
Moons: 0
Planet type: terrestrial
Toasty Conditions
Venus has the hottest atmosphere out of all of the planets. This deadly atmosphere is made up of mostly carbon dioxide with clouds composed of sulfuric acid, making a very thick blanket over the planet. As a result, Venus appears as the brightest planet to us because the thick clouds reflect about 70% of sunlight back into space and the heat on Venus builds up to extremely high temperatures since the heat has trouble escaping into space after the surface is heated by the Sun. With such extreme conditions, you may laugh at the idea of life on Venus, however, at about 50 kilometers (30 miles) from the surface of Venus, temperatures range from 30 to 70 degrees Celsius (86 to 158 degrees Fahrenheit) and the atmospheric pressure is similar to that of Earth, which could possibly allow “extremophile” microbes to exist at this point in the atmosphere.
Mantle Plumes
Just like on Earth, mantle plumes that rise from deep within the mantle of Venus cause much of the volcanic activity that we see on the surface. A mantle plumes is an upwelling of magma under the surface or a column of hot magma that is hotter than the surrounding mantle material, causing it to rise within the mantle until it reaches the crust, where it is forced to spread out over a large area like the top of a mushroom. The extremely hot temperatures of the top of this plume heats the lithosphere of the planet until it actually melts. The melting of the lithosphere allows magma chambers to form through the crust, which feed the volcanoes that form above them. The part of the surface where the top of the mantle plumes hides beneath is called a hot spot, and it is the reason that we tend to the majority of volcanoes forming over these hot spots.
Craters
Craters are spread uniformly over the surface of Venus, and they all look new. This is because the older craters were washed out by lava flows from earlier periods. The craters are large, which suggests that smaller meteorites burn up in the thick atmosphere of Venus before hitting the surface. 1000s of craters are spread across the rolling plains on Venus, and the rolling plains make up 65% of the geography of Venus. The impact craters are created by meteors, comets, or asteroids striking the surface, leaving a bowl that extends below the surface, while volcanic craters are left over from the outward explosion of a volcano and are elevated from the ground. We can see these features on the Earth as well.
Deadly Geography
Venus as seen from above is very cloudy and mysterious, so how do we see the land features below? Our knowledge of the surface comes primarily from extensive radar imaging of the planet from both Earth-based devices and space probes. We now have a detailed radar picture of the Venusian surface and all the activity that happens below the clouds.
The Mead Crater is one of the largest impact craters known to exist on Venus. The crater is 170 miles or 274 kilometers in diameter.
The Barringer impact crater in Arizona.
Volcanic crater from Italy’s Vesuvius Volcano.
Volcanism
Venus is not only full of craters, but also more volcanoes than any other planet in the solar system with the total number being over 100,000 or even maybe more than 1,000,000 volcanoes strewn across the surface.
Scientists at Washington University in St. Louis released this stunning map, displaying 85,000 volcanoes on Venus found using radar imagery from the 1990s Magellan mission.
Shield Volcanoes
Venus has over 150 of these huge shield volcanoes, which are mostly between 100 and 600 kilometers across with heights ranging mostly between 0.3 and 5 kilometers. These volcanoes, which can also be seen on Earth, are characterized by gentle slopes and a central vent that can be seen in the middle. They are known to form from basaltic lava that flows quickly due to a low viscosity. When the lava flows out of the central vent, it flows far down the sides of the volcano before hardening, adding to the cooled and hardened layers of lava beneath it that have built up the volcano over time. This is different from a composite volcano because shield volcanoes erupt more often but their eruptions are not nearly as violent.
Pancake Domes
Known for their flap-jack appearance, these pancake volcanoes are widely scattered on Venus and are often found near coronae or tesserae. Unlike shield volcanoes, which form from multiple eruptions of fast flowing eruptions over time, a pancake dome forms from one large, slow eruption of viscous or sticky lava. Pancake domes are very wide with flat tops and are usually less than 1000 meters in height. The cooling and withdrawing of lava on these volcanoes creates the cracks and faults that can often be seen. The pits that can be seen in the center of pancake domes are not the central vents from which the lava flows like on shield volcanoes, but are more likely to have formed after the one, large eruption as gasses escaped from the magma and the dome cooled and shrank.
While volcanism here on Earth is often the result of shifts in tectonic plates, Venus has shown no evidence of plate tectonics so far. There are no long volcano chains or clear continent-like regions such as on Earth, making volcanism on Venus more regional and less organized.
A chain of pancake domes east of Alpha Regio with clear crack patterns.
A group of pancake domes called Carmenta Farra. The largest dome is 65 kilometers across and roughly a kilometer high.
Ticks
The volcanic features called “ticks” are named after the parasitic insect seen on Earth, and are similar to pancake domes in many ways. The “body” of the tick is a mostly flat area with a central pit or vent structure. However, ticks contain arrays of short, radial ridges that can be seen as the “legs” of the tick. The “leg” ridges could outline avalanche scars, or they could be dikes running out from the “body,” which are bodies of rocks that cut across the layers of their surroundings.
This tick is near the edge of Eistla Regio and is about 66 km (41 miles) across with a central “body” that is about 35 km (22 miles) wide.
Coronae
Coronae are another huge indicator of the highly volcanic surface of Venus. They are large, circular volcanic features that are typically hundreds of kilometers across and have only been seen on the Venusian surface and the surface of Uranus’s moon Miranda. These unique circles are thought to form from mantle plumes, which push hot material up into the crust, forming a dome above the surface, which then collapses in the center and flattens out as the magma cools and leaks out of the sides.
Artemis Corona is the largest Corona that we have found on the Venusian surface. At nearly 2600 km in diameter, it would take up most of the United States.
Tesserae
Another pattern we have found strewn across the surface of Venus are Tesserae, which are completely unique to the hot planet as far as we know. A tessera is a region that is highly deformed and complex, justifying its name, which translates to “mosaic tile” in Latin. Radar images of tesserae show elevated, rugged terrain with different trends of ridges (narrow hilltops) and troughs (depressions) that cut across one another at many different angles. Tesserae make up almost 8% of the entire surface of Venus and are the oldest features on the Venusian surface. The largest tessera, Ovda, is 8,600,000 square kilometers or about 2% of the surface area of Venus. Due to the complexity of these structures, no single process can explain how they formed. The most accepted models to explain the formation of tesserae are mantle downwelling and pulsating continents. Mantle downwelling due to mantle convection that pushed mantle material down, causing thickening and compression of the crust, which creates tessera terrain. In the pulsating continents model, low density crust that forms continental regions undergo compression from the heating of the surrounding mantle, squeezing the lithosphere and forming the compressional and elevated features of the tessera.
Alpha Regio, the first and one of the oldest features to be identified on Venus using radar.
