por Venus It is the second closest planet to the Sun in the solar system and the closest to Earth in size and mass. It is visible as a beautiful star, the brightest after the Sun and the Moon. Therefore, it is not surprising that it has powerfully attracted the attention of observers since ancient times.
Because Venus appears at sunset at certain times of the year and at sunrise at others, the ancient Greeks believed that they were different bodies. As the morning star they called him Phosphorus and during the evening appearance he was Hesperus.
Later Pythagoras assured that it was the same star. However, around 1600 BC the ancient Babylonian astronomers already knew that the evening star, which they called Ishtar, was the same one they saw at dawn.
The Romans also knew this, although they continued to give different names to the morning and evening apparition. Also the Mayan and Chinese astronomers left records of the observations of Venus.
Each ancient civilization gave her a name, although eventually the name of Venus, the Roman goddess of love and beauty, the equivalent of the Greek Aphrodite and the Babylonian Ishtar, prevailed.
With the advent of the telescope, the nature of Venus began to be better understood. Galileo observed the phases of it at the beginning of the 17th century and Kepler carried out calculations with which he predicted a transit for December 6, 1631.
A transit means that the planet can be seen passing in front of the Sun. In this way Kepler knew that he could determine the diameter of Venus, but he died before seeing his prediction fulfilled.
Later in 1761, thanks to one of these transits, scientists were able to estimate for the first time the Earth-Sun distance at 150 million kilometers.
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General characteristics of Venus
Despite the fact that its dimensions are very similar to those of Earth, Venus is far from being a hospitable place, since to begin with, its dense atmosphere is composed of 95% carbon dioxide, the rest is nitrogen and trace amounts. of other gases. The clouds contain droplets of sulfuric acid and tiny particles of crystalline solids.
That is why it is the hottest planet in the solar system, although it is not the closest to the Sun. The accentuated greenhouse effect caused by the thick atmosphere rich in carbon dioxide is responsible for the extreme heat on the surface.
Another distinctive feature of Venus is its slow, retrograde spin. A traveler would watch the Sun rise in the west and set in the east, a fact discovered thanks to radar measurements.
Furthermore, if it managed to stay long enough, the hypothetical traveler would be very surprised to realize that the planet takes longer to rotate around its axis than it does to rotate around the Sun.
Venus’s slow rotation makes the planet almost perfectly spherical and also explains the absence of a strong magnetic field.
Scientists believe that the magnetic field of the planets is due to the dynamo effect associated with the movement of the molten metal core.
However Venus’s weak planetary magnetism originates from the interaction between the upper atmosphere and the solar wind, the stream of charged particles that the Sun continually emits in all directions.
To explain the lack of a magnetosphere, scientists consider possibilities such as that Venus lacks a molten metal core, or that perhaps it does, but that heat inside it is not transported by convection, a necessary condition for the existence of the magnetosphere. dynamo effect.
Summary of the main physical characteristics of the planet
-Mass: 4.9×1024 kg
-Equatorial radius: 6052 km or 0.9 times the radius of the Earth.
-Shape: it is almost a perfect sphere.
-Average distance to the Sun: 108 million km.
–orbital inclination: 3.394º with respect to the terrestrial orbital plane.
-Temperature: 464ºC.
-Gravity: 8.87 m/s2
-Own magnetic field: weak, 2 nT intensity.
-Atmosphere: yes, very dense.
-Density: 5243 kg/m3
-Satellites: 0
-Rings: does not have.
Translation movement
Like all the planets, Venus has a translation movement around the Sun in the form of an elliptical orbit, almost circular.
Some points in this orbit bring Venus very close to Earth, closer than any other planet, yet most of the time it actually passes quite far from us.
The mean radius of the orbit is about 108 million kilometers, therefore Venus is approximately 30% closer to the Sun than Earth. A year on Venus lasts 225 Earth days, since this is the time it takes for the planet to complete one orbit.
Venus motion data
The following data briefly describe the movement of Venus:
-Mean radius of the orbit: 108 million kilometers.
–orbital inclination: 3.394º with respect to the terrestrial orbital plane.
-Eccentricity: 0.01
–average orbital velocity: 35.0 km/s
–Translation period: 225 days
–Rotation period: 243 days (retrograde)
–sun day: 116 day 18 hours
When and how to observe Venus
Venus is very easy to locate in the night sky; after all, it is the brightest object in the night sky after the Moon, as the dense cloud cover that covers it reflects sunlight very well.
To easily locate Venus, it is enough to consult any of the many specialized websites. There are also applications for smartphones that facilitate your exact location.
Since Venus is within Earth’s orbit, to find it you have to look for the Sun, looking east before sunrise, or west after sunset.
The optimal time for observation is when Venus is between the inferior conjunctionseen from Earth and a maximum elongation, according to the following diagram:
When Venus is in inferior conjunction, it is closest to Earth and the angle it forms with the Sun, seen from Earth -elongation- is 0º. On the other hand, when it is in superior conjunction, the Sun does not allow it to be seen.
Hopefully Venus can still be seen in broad daylight and cast a shadow on very dark nights, without artificial lighting. It can be distinguished from stars because its brightness is constant, while the stars flicker or twinkle.
Galileo was the first to realize that Venus goes through phases, just like the Moon -and Mercury-, thus corroborating Copernicus’s idea that the Sun, and not the Earth, is the center of the solar system.
Rotatory motion
Venus rotates clockwise as seen from Earth’s north pole. Uranus and some satellites and comets also rotate in this direction, while the other major planets, including Earth, rotate counterclockwise.
In addition, Venus takes its time in executing its rotation: 243 Earth days, the slowest among all the planets. On Venus, a day is longer than a year.
Why does Venus rotate in the opposite direction to the other planets? Probably in its beginnings, Venus rotated rapidly in the same direction as everyone, but something must have happened for it to change.
Some scientists believe it is due to a catastrophic impact that Venus had in its remote past with another large celestial object.
However, mathematical computer models suggest the possibility that chaotic atmospheric tides have affected the planet’s unsolidified mantle and core, reversing the direction of rotation.
Possibly both mechanisms have played a role during the stabilization of the planet, at the beginning of the solar system.
The greenhouse effect on Venus
On Venus, clear and cloudless days do not exist, so it will be very difficult for a traveler to observe the sunrise and sunset, which is what is commonly known as day: the sun day.
Very little sunlight makes it to the surface, as 85% is reflected by the cloud canopy.
The rest of the solar radiation manages to heat the lower atmosphere and reaches the ground. Longer wavelengths are reflected and retained by clouds, known as the greenhouse effect. This is how Venus became a gigantic furnace with temperatures capable of melting lead.
Virtually anywhere on Venus is this hot, and if a traveler got used to it, they would still have to endure the enormous atmospheric pressure, which is 93 times that of Earth at sea level, caused by the great 15-kilometre cloud layer. of thickness.
As if that were not enough, these clouds contain sulfur dioxide, phosphoric acid and highly corrosive sulfuric acid, all in a very dry environment, since there is no water vapor, just a small amount in the atmosphere.
So despite being covered in clouds, Venus is completely arid, and not the planet full of lush vegetation and swamps that science fiction authors imagined in the mid-20th century.
water on venus
Many scientists believe that Venus once had oceans of water, because they have found small amounts of deuterium in its atmosphere.
Deuterium is an isotope of hydrogen, which combined with oxygen forms the so-called heavy water. Hydrogen in the atmosphere easily escapes into space, but deuterium tends to leave residue, which may be a clue that water once existed.
However, the truth is that Venus lost these oceans -if they ever existed- about 715 million years ago due to the greenhouse effect.
The effect began because carbon dioxide, a gas that easily traps heat, concentrated in the atmosphere instead of forming compounds on the surface, to such an extent that water evaporated completely and stopped accumulating.
Meanwhile, the surface got so hot that carbon in the rocks sublimed and combined with atmospheric oxygen to form more carbon dioxide, fueling the cycle until things became extreme.
At present Venus continues to lose hydrogen, according to the information provided by the Pioneer Venus mission, so it is unlikely that the situation will be reversed.
Composition
There is little direct information about the planet’s composition, since seismic equipment does not survive long on the corrosive surface, and the temperature is hot enough to melt lead.
Carbon dioxide is known to predominate in the atmosphere of Venus. In addition, sulfur dioxide, carbon monoxide, nitrogen, noble gases such as helium, argon and neon, traces of hydrogen chloride, hydrogen fluoride and carbon sulphide have been detected.
The crust itself is abundant in silicates, while the core surely contains iron and nickel, like Earth’s.
The Venera probes detected the presence of elements such as silicon, aluminum, magnesium, calcium, sulfur, manganese, potassium, and titanium on the surface of Venus. There may also be some iron oxides and sulfides, such as pyrite and magnetite.
Internal structure
Gaining information on the structure of Venus is a feat, taking into…