Let's talk about the planet Venus.
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The planet Venus is located 108 million km from the Sun, so the planet Mercury is the closest to our star. Venus takes 224.7 Earth days to orbit the Sun, so one year on Venus is shorter than one Earth year: that's 0.6 x Earth year (1 year on Venus = 60% Earth year). And it takes 243 days to rotate on its axis of rotation, in backward mode please, it has a retrograde rotation. If you were to stand on the surface of Venus, you would notice that the Sun rises in the west instead, while you are used to seeing the Sun rise in the east on Earth. In our solar system, only 2 planets, Venus and Uranus, have this retrograde rotation. But be careful, don't confuse it with the sense of the movement of the revolution which is the same for all 8 planets, without exception: Venus revolves around the Sun in the normal sense, prograde, of the solar system, at an average of 35 km/s. Its orbit is elliptical like the other planets, although the degree of ellipticity is not the same for all. This is what astronomers call eccentricity.
Venus is part of the 4 telluric planets of the solar system, 4 of the inner planets of the system, and of all 8 planets she and Mercury do not have moons.
There is no life on this planet, we know that it is only on Earth that has life from what we have come to understand so far in all scientific research: we must protect our little planet Earth very much. Let's tell the politicians that too.
Its position inside the system allows us to see when it passes in front of the Sun.
Yes, it's a kind of eclipse, but in relation to its very small angular diameter, it can't darken the Earth like a total solar eclipse when our Moon passes in front of the Sun. Astronomers call this eclipse category transit instead.
Well, the transit of Venus is a rare phenomenon, because it usually takes a century to see a pair of eclipses.
And yes, the astronomers prefer to classify them by 2. As in the century we are in, there were transits of Venus in front of the Sun in 2004 and 2012, and the next dates for the pair of transits are 2117 and 2125. Me, I will not be there. I don't know about you?
We could say that the planet Venus is similar to the Earth if we take into account its size (12 104 km in diameter), its mass (0.8 x the mass of the Earth), the amount of matter gathered to form it, and also its volumetric mass (5240 kg/m3). Gravity on its surface is 0.9 times Earth's gravity. But there are also differences between these planets: first, it is covered with very thick clouds made mainly of sulfuric acid. This makes it difficult for astronomers to observe its surface from Earth, so they cannot see it using visible light. Only thanks to the light of radio waves, so radio astronomy, they get to see relief on its surface....
It has an atmosphere rich in carbon dioxide, but the clouds contain mostly sulfuric acid mixed with "sulfur" dust, which causes it to appear yellow. Astronomers think it would be active volcanoes on its surface that would cause the presence of "sulfur" in the clouds, as from time to time there would be renewal of this matter in the atmosphere of Venus.
A lot of gases in the planet's atmosphere makes it reflect, from above, 75% of the Sun's light reaching it, which is what astronomers technically call albedo.
So it appears as a very bright star to us in the morning sky just before the Sun rises or in the evening when the Sun has just set, depending on the time on its orbit. That's why they call it the "morning star", well, in our culture, they call it the "bayakou star", because it seems that the bayakou used to watch for it to appear in the sky at dawn, then they quit their job and go home quickly so that people will not see them anymore...well, "there is no such thing as a stupid profession!", except bandits, of course.
We must also know that the temperature on the surface of the planet will not play at all, it is the highest temperature of all the planets in the solar system. It reaches 480oC. You heard, you would understand that the planet Mercury that is closest to the Sun would be hotter, then Venus that is farthest from the Sun compared to Mercury is the hottest.
All this, because it has a thick atmosphere with a lot of carbon dioxide and "sulfur" in it that also keeps the heat the planet is giving. It is a phenomenon called the greenhouse effect where the rays of the Sun that reach its surface, and reflect in the form of IR (infrared), do not really get out to go back into space. Most of the IR (infrared) that returns to the surface of Venus to make it even hotter...all these go-and-back motion of IR (infrared) rays cause the temperature to increase greatly: this is called the runaway greenhouse effect...thanks to carbon dioxide and "sulphur" dioxide gases in the atmosphere.
Well, doesn't that remind us of what is happening on Earth right now? We don't have this full amount of sulfur dioxide and carbon dioxide in our atmosphere, fortunately, but thanks to the industrial revolution that helps us in its own way, and thanks also to water vapor and other greenhouse gases released into our atmosphere, we start to have great heat on Earth too... Well, it's not at the level of Venus, it's not yet, but when we understand what's happening on this planet, it makes us think and act against climatic change that is being installed on Earth. This affair is not completely clear for all countries. There are those who don't agree, even if we haven't found a reserve planet to migrate to...well, in the meantime we cross from planet to planet, we're crossing from country to country as climate refugees. we, Haitians, we are used to this refugee issue, even though at the moment it is due to insecurity and bad politic...
Let's go back to the subject which is Venus. We will notice how the study of Venus can allow us to understand the functioning of the Earth: we do not always have to believe that astronomy is a science that is only above!
Optical light, that is the normal light that people can see, does not allow astronomers to see what is happening under the atmosphere of Venus, well, we have already said it. Since the 1960s, the Americans and the Soviets began to put probes around Venus to study the planet, but the armor of the Soviet devices was stronger, and they also had bigger rockets to carry these big heavy things into space. This is why they were the only ones who managed to land a probe, Venera 7, on the surface of this planet in 1970. So, until the 1980s, scientists managed to obtain valuable photos and other data on the surface. They managed to confirm, for example, the high temperature on the surface and the structure of the cloud layers from below. They also managed to understand the basaltic structure of some rocks on the surface.
The surface of Venus is very hot, as we said recently, 480o Celsius, but the more you go up in altitude, the temperature goes down, and the atmospheric pressure, which is 98 times that of Earth, also goes down in altitude. That's because the gas density of the atmosphere naturally decreases the higher you go. To give you an idea of how strong the atmospheric pressure is on the surface of Venus, in comparison, you may have to go deep, 920 meters below sea level on Earth...not a small pressure, my friend!
The surface of Venus is very flat, although there are some small hills that are not steep. Do not be surprised to know that its surface does not have as many craters as the surface of Mercury or the Moon. That's because the atmosphere intercepts and destroys meteorites that would try to enter. The biggest ones do survive, but most of the others are destroyed from the top of the atmosphere.
Moreover, the dynamism of the surface, and the volcanoes, can reshape the surface to make many impacts, which would happen anyway, deleted... It would be similar to the Earth, there too, except that the Earth also has a global movement of tectonic plates that Venus does not have. On the surface of Venus, it is yellow, if I can say it like this: it is not the same as on Earth, because the atmosphere has a series of large yellow clouds that are permanently covering, and there is sulfuric acid in suspension that usually gives little rain, but the acidic liquid does not reach the surface because of the high atmospheric pressure near the surface.
Well, on the surface, there are active volcanoes. There used to be doubts about the volcanic activity, but since the NASA probe discovered, in 2015 and in 2020 also while the Solar Parker probe was on its way, some large lightning strikes like what usually occurs in some volcanoes on Earth, astronomers have confirmed their old suspicions. In addition, "sulfur" is a very volatile element, that means even though it is there, it is not supposed to be there for long, so you would not expect to continue to find so much "sulfur" in the atmosphere. This means there is a continuous renewal that takes place through the activity of the volcanoes.
Astronomers have identified 2 continents on Venus: they are called Aphrodite Terra and Ishtar Terra, 2 names from mythology that represent the goddess of love... well... yet the name of the planet goes in this sense, we understand.
In fact, these 2 continents are 2 areas where the surface rises higher than the rest of the flat area that covers 65% of the planet. Thanks to probes that are in orbit around the planet, using radio waves to penetrate the atmosphere, scientists have managed to map the entire planet, they know all the reliefs. For example, we know that the continent of Itshar Terra, located in the northern hemisphere of the planet, is the size of Australia on Earth. It is surrounded by a series of mountains; one of them is very tall, they gave him the name Maxwell and it has an altitude of 11 km, which is higher than Mount Everest on Earth which measures only 9 km, and which is the highest mountain on Earth. Well, Aphrodite Terra itself, which stretches over 16,000 x 2,000 km, is half the size of Africa. So, we must understand, they are continents relative to the global level of the rest of the planet.
There is no water on Venus. Has there been water long time ago? It would seem that there could have been water in the past, but with the temperature it has, as we have just seen, all the water would have evaporated a long time ago.
For the internal structure of the planet, there is still no good data, especially that landing and staying long on the surface is not easy: even the Soviet probes did not last long on the surface. The amount of time they made is to quickly send information to the Earth, before they melt. But astronomers have come to understand that there is a mantle that is active in convection, and the core, which is made of iron and nickel, cannot produce a strong magnetic field, especially since the rotation of the planet takes time, remember, I told you that it takes 243 terrestrial days, and don't forget, it's retrograde. There are some small local magnetic fields, but not as strong as Earth's.
In summary for the exploration of this planet, there are 4 space probes that managed to do this work: there were the Veneras, we talked about them already, the only device family that managed to land and do its work for a while; there were Mariner 2 in 1962 and Magellan in the 1990s, which were sent by NASA. And there was Akatsuki, the country of Japan that launched it, and managed to put it in orbit around the planet in 2015.
Venus remains a beautiful planet up in the sky, it does not bear its name for nothing! We have just summarized what we know about it, but there are projects to explore it even more. We will follow, stay tuned to the channel, share, like. Captain Astro is here to help you understand and you can ask any questions you want about astronomy on social networks or on phone or WhatsApp at 38407775. Keep it up despite the problems our country is going through.
See you soon.n.
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