SOLAR SYSTEM FAMILY-FACTS ABOUT VENUS, THE HELLISH PLANET

 Our ancestors were perhaps bewildered to see an extremely bright star just after sundown or before sunrise. Being the second brightest object in the night sky, succeeding the moon, this star-like object was capable of casting shadows on a moonless night. Probably because of its brightness, this star(actually a planet) was named after Venus-the goddess of love, beauty and intense passion, occupying the human hearts through generations of philosophy, art, literature and science. Though Venus represents beauty and fertility, in reality this planet is actually analogous to hell, filled with toxic clouds of sulfur dioxide gas and extreme heat. 

A Bit of Mythology: The word Venus directly comes from the Latin word ''VENUS'', meaning love. According to Roman mythology goddess Venus never had any proper parents. Her father was Uranus, the father of Saturn and grandfather of Jupiter; while her mother was the Sea. Venus has always been depicted as the goddess of love, and because of being born from the sea, she had the ability to absorb a male's passion and unite him with the female's virtuous affection. She also had the ability to grant military victory on one hand, and save men and women from sexual vice and thrust them with virtue.

                                        Venus also shared attributes with her Greek counterpart ''Aphrodite'', the goddess of love, passion, procreation and sensuality. But, the early Greeks never considered Aphrodite as a personification of planet Venus. They saw that star as two entirely different celestial objects-the morning star and the evening star. The morning star was called ''Phosphoros'' or ''Bringer of light'' and the evening star was ''Hesperos'' or ''the Star of the Evening''. Venus has also been found as a divine being in other ancient religions and cultures, like the Babylonians knew her as ''Nisi'anna'' which translates to ''divine lady, illumination of heaven''. The ancient Indians named this planet "Shukra'' after a powerful saint, ''Saint Shukra'', which translates to ''clear, pure, brightness or clearness''.

Basic Facts: Venus is the second terrestrial planet of our solar system and is often called the sister planet of Earth, owing to their similar shape and size. Venus has an extremely dense atmosphere and display phases like our moon. The planet is seen as a bright starry dot near the eastern hemisphere before sunrise, and near the western hemisphere after sunset.

Venus against a black backdrop/Credits: Photo by form PxHere   

Planetary Characteristics:

• Orbital and Rotational Characteristics- Venus completes its orbit around the Sun once in every 225 Earth days, roughly at a distance of 108 million km from our parent star, and in a nearly circular orbit with an eccentricity of 0.01 only. But, the planet does not spin in a counter-clockwise direction about its axis, like our Earth. Venus spins in a clockwise direction, from east to west and in an extremely slow pace where a single Venusian day lasts for nearly 243 Earth days. On Venus, the Sun appears to rise from the western horizon and set in the eastern horizon. But an observer there would not be able to notice this difference because of the thick clouds in the Venusian atmosphere. The dense atmosphere consisting of SO₂ and CO₂ gases blocks the incoming solar radiation. And consequently the daytime sky always remains hazy(obviously there's a yellowish glow) and a total absence of light can only reveal to an observer that it is night. This slow rotation has helped the planet to maintain a spherical shape, compared to our Earth who has a bulge near the equator. But, the reason for the clockwise rotation of the planet is still under heated debate. Some scientists speculate that during its formation, the planet got knocked off by another celestial object which tilted the planetary axis by an angle of 90 degrees. Others speculate that Venus simply reversed its direction of rotation simply because of geological processes deep between the mantle and the core. Whereas, another model proposes that the rotation might have slowed down due to extreme atmospheric drag and tidal forces. However, a planet just reversing its direction of rotation is a bit weird and it has still been an open question for astronomers.

• Internal Structure- Scientists lack seismic data about the planet. But by analyzing Earth's geology it is speculated that Venus has a liquid core, a mantle and a crust. Venus has an equatorial radius of 6051 km, a density of 5.243 g/cc compared to Earth's equatorial radius of 6371 km and density of 5.51 g/cc.

• Surface Geology- Venus has an extremely thick atmosphere and as a result the planetary surface remained subject to fantasy until the unmanned Venera missions sent back substantial data. From the Venera data it was found that the surface has been relatively young and has gone recent resurfacing with respect to geologic time-frames. The planet has got two highland continents on both the northern and the southern hemispheres. The northern hemisphere has been named ''Ishtar Terra'', after the Babylonian goddess of love ''Ishtar''. While the southern hemisphere has been named ''Aphrodite Terra'', after the Greek goddess of love, Aphrodite. The Venusian surface is laden with a few impact craters, mountains, valleys, plains, ridges along with some pancake shaped volcanic flat tops called ''farra'', which ranges from 20 to 50 km. There are also some star-like fractures called ''novae'', some spider webs called ''arachnoids'' and circular rings of volcanic origins called ''coronae''. Venus has been volcanically and geologically active, though there has not been any recent volcanism on the planet. The surface consists of basalt, a type of volcanic rock which suggests that volcanism played the highest role in shaping this planetary surface. Venus has the highest number of volcanoes among all the terrestrial planets, and there are more than a thousand volcanic structures found on the surface. But unlike Earth, Venus has no tectonic plates.

The black dot is the planet(Venus) during a transit/Credits: Mswggpai at en.wikipedia, CC BY-SA 3.0

• Surface Temperature- Venus is the hottest planet in our solar system, with a surface temperature greater than that of Mercury which is also the closest planet to the Sun. The thick Venusian atmosphere filled with toxic amounts of SO₂ and CO₂ generates a strong greenhouse effect. This greenhouse effect traps solar radiation and heats up the surface to a staggering 735K(462℃) compared to a surface temperature of 700K(427℃) on Mercury and 288K(15℃) on Earth. 

• A Thick Atmosphere- As mentioned earlier, Venus has an extremely dense and poisonous atmosphere with 96.5 parts of CO₂, 3.5 parts of N₂ and traces of other gasses like SO₂, Ar, H₂O, CO, He and Ne. The mass of the atmosphere is 93 times that of Earth and the surface pressure is 92 times greater than mean sea level pressure on Earth. Although Venus is the goddess of love, in reality this place is a million times hellish than hell itself. No form of earthly life could ever imagine surviving in this hell of a place. Even sophisticated machines failed to operate for more than an hour as their circuits were scorched to death by the extreme heat. But back in the past, Venus had oceans of liquid water, a good atmosphere and was probably a fertile planet. Planetary models suggest that when our Sun was young, Venus resided within the habitable zone and contained liquid water. With time the solar luminosity increased as the Sun evolved and the habitable zone shifted towards Earth. Probably due to this reason, Venus was bombarded with intense solar radiation and as a result the oceans started to evaporate. Water vapor, being a potent greenhouse gas gradually aided in the global warming of the planet, which in turn dried up the ocean faster and faster, thereby releasing the trapped carbon from the ocean floor. This carbon kicked off the runaway greenhouse effect and in due course this beautiful planet lost all her charm and transformed into a toxic world.

• Magnetic Field- Venus has got a very weak magnetic field. This weak field is not generated from the geodynamic processes within the core, but from the interaction of the solar wind with the planet's ionosphere. The absence of a geodynamo reveals that the core must have been shut down due to some resurfacing events, cooled and turned into a solid lump or the planet does not have a solid core. Because of a weak magnetic field, Venus is also devoid of a strong magnetosphere and is thus incapable of providing any protection to itself from the ionizing solar radiation, and cosmic rays. The weak magnetosphere makes it possible for the solar wind to interact directly with the Venusian atmosphere. This interaction creates ionized hydrogen and oxygen, which ultimately escapes from the ionosphere. This erosion has also contributed towards the loss of water vapor from its atmosphere. However the planet is likely to retain the heavier molecules viz., SO₂ and CO₂, as these gases stay much closer to the surface.

• Natural Satellite(s): Venus has no natural satellite(s) as of today.

Biological Considerations: Venus is not technically fertile and no sort of life form, even ultra-primitive unicellular organisms have been found till date. Scientists speculate that during the early epoch when Venus had water, life would have had a chance to spurt and evolve, but that's unconfirmed and awaits further investigation. But like a silver lining on a dark cloud, scientists have recently found the presence of phosphine in the atmosphere. Phosphine is an extremely poisonous and lethal gas which is produced from a variety of chemical processes and by biological organisms. The possibility of phosphine existing among the Venusian clouds has added fuel to the ongoing debate about the existence of extraterrestrial life forms. Phosphine has been found in concentrations of 20 ppb(parts per billion) which is significantly higher than what can be produced from known chemical reactions. So this excess of phosphine hints at some alien biological organisms at work, or some completely exotic chemical reaction that doesn't occur on Earth. However there's only one way to find out the truth and that is in-situ exploration of our sister planet in near future.

The Venusian surface remains shrouded by a thick atmosphere/Credits:Pablo Carlos Budassi, CC BY-SA 4.0, via Wikimedia Commons

Observations and Explorations: Venus have been observed since ancient times as this star-like object would cast shadows on a moonless night. Being the third brightest object of our sky, after the Sun(first) and moon(second), the goddess of love dwarves all other objects in brightness and clarity.

• Observations- Because of being closer to the Sun, the planet sometimes disappears from the western horizon for days, and reappears again on the eastern horizon, and vice versa. This irregularity made some of the ancient cultures believe that the same planet was two different stars; the morning star on the eastern hemisphere and the evening star on the western hemisphere. The Greeks called them Phosphoros and Hesperos, and the Romans called them Lucifer and Vesper. The Chinese knew the former as ''The Great White'' or ''The Opener of brightness'', while the latter was called ''The Excellent White One''. Nevertheless, the Sumerians believed the morning star and the evening star to be the same. 

                                   The first telescopic observation was made by the famous Italian astronomer Galileo Galilei during the early 17th century. His discovery of the planet showing phases like the moon gave proof that Venus revolves Around the Sun and not Earth. The transit of Venus was predicted and observed by another astronomer Jeremiah Horrocks and William Crabtree during the mid 17th century. A lot was not discovered about Venus till the advent of modern astronomical techniques during the 20th century. Thus all fantasy and fiction about the goddess of love ceased after modern astronomical observations in visible, ultraviolet, infrared wavelengths and in radar. Finally, unmanned explorations began after the mid 20th century.

• Explorations- There has been a dozen unmanned explorations of Venus. They are listed below in order.

1. The Soviet Russia was the first nation to conduct explorations of Venus during their ''Venera Program'' in 1961, and sent a robotic space probe to explore the planet.      
2. The United States tasted their scoop of success in exploring Venus with the Mariner-2 of the ''Mariner Mission'' on December 14, 1962 and became the first nation to complete a successful interplanetary mission. Mariner 2 passed 34,800 km above the Venusian surface and collected data on the planetary atmosphere. 
3. The Soviet nation successfully entered the Venusian atmosphere with the help of their Venera 4 spacecraft. Venera 4 determined the surface temperature, and its dense carbon dioxide atmosphere. The data was analyzed combining the data from the Mariner 5 mission of the United States, which did a flyby of Venus on October 18, 1967.
4. Mariner 10 by NASA, took photos of the planetary atmosphere in the ultraviolet spectrum, while using a gravity assist from Venus en route to Mercury.
5.  The Soviet Nation did a successful soft landing on Venus with their Venera 7 space-craft from the Venera missions that lasted between 1961-1982. At first the Venera crafts could only transmit a few black and white photos of the Venusian surface. Much later colored photos were sent by Venera 13 & 14.
6.  NASA obtained additional data from the ''Pioneer Venus Project'' in 1978. 
7. During 1983 the Soviets terminated their Venera program after placing Venera 15 & 16 in orbit around the planet and was designed to map the surface. 
8.  Other explorations include the Vega 1 and Vega 2 by the Soviet Nation. And because of so many Russian attempts to explore Venus, recently some of their officials declared it to be a ''Russian Planet''. Several other probes also visited Venus en route to other distant worlds. These include the ''Galileo mission'' in 1990, ''Magellan'' in 1994, ''Cassini-Huygens'' in 1998 and  MESSENGER in 2006. 
9. The ESA sent ''Venus Express'' which reached Venus in April 2006 and provided data on the planet's atmosphere. 
10.   More upcoming missions are being developed by ROSCOSMOS, NASA and ISRO.

 

Very Distant Future: Presently, terraforming a planet is still within the domains of fantasy and fiction. But it can be assumed that after a thousand years from now humans would become advanced enough to terraform planets. Since Venus is Earth's sister planet, so she can act as a refuge for human beings if there is any substantial threat to Earth and mankind. The idea of terraforming Venus obviously started with the great Carl Sagan, who proposed introducing genetically modified bacteria in the Venusian atmosphere so that they can convert the atmospheric CO₂ into organic molecules. Soon other people followed him with their ideas of terraforming Venus. It was once proposed that introduction of hydrogen can lower the atmospheric pressure by creating graphite and water, whereas calcium and magnesium can store atmospheric carbon in the form of carbonate molecules. Solar shades can be used to divert the incoming solar radiation, which is twice than what we receive on Earth. Other suggestions include changing the rotational speed of the planet or else building floating structures much above the clouds within the planet's atmosphere. Although, none of these can be achieved within the next decade, but we can always hope for a bright and sustainable future. 

                                              But the very far future is quite bleak for Venus. Since our star, the Sun would eventually become a red giant, its luminosity and size will steadily increase. And because of this increase in size, Venus would ultimately be eaten by the Sun. 

The twin planets-Earth & Venus/Credits:Needpix.com

Some Quick Facts!

References:

1. https://en.wikipedia.org/wiki/Venus 
2. https://solarsystem.nasa.gov/planets/venus/overview/