The atmosphere is a gas shell of the planet, moving along with the planet in the world space as a whole. Almost all the planets of our solar system have their atmospheres, but only the earthly atmosphere is able to maintain life. In the atmospheres of the planets there are aerosol particles: solid dust raised from the solid surface of the planet, liquid or solid particles resulting from the condensation of atmospheric gases, meteoric dust. Consider in detail the composition and features of the atmosphere of the planets of the solar system.
Mercury. On this planet there are traces of the atmosphere: helium, argon, oxygen, carbon and xenon are fixed. The pressure of the atmosphere on the surface of Mercury is extremely small: constitutes a two-dollar phase from normal earthly atmospheric pressure. With such a sparseness of the atmosphere, it is impossible to form the formation of winds and clouds, it does not protect the planet from the heat of the Sun and cosmic radiation.
Venus. In 1761, Mikhail Lomonosov, observing the passage of Venus on the Disk of the Sun, noticed a thin rainbow rims surrounding the planet. So the atmosphere of Venus was opened. This atmosphere is exceptionally powerful: the surface pressure was 90 times greater than that of the earth's surface. Venus atmosphere by 96.5% consists of carbon dioxide. Not more than 3% falls on the share of nitrogen. In addition, the impurities of inert gases (first of all, argon) were found. The greenhouse effect in the atmosphere of Venus raises the temperature of 400 degrees!
Sky on Venus has a bright yellow-green shade. Foggy haze stretches up to a height of about 50 km. Next to the height of 70 km are clouds from small drops of sulfuric acid. It is believed that it is formed from sulfur dioxide, the source of which can be volcanoes. The speed of rotation at the level of the upper boundaries of the clouds is different than above the surface of the planet. This means that the Equator of Venus at an altitude of 60-70 km is constantly blowing a hurricane wind at a speed of 100-300 m / s in the direction of the planet movement. The most upper layers of the atmosphere of Venus consist almost entirely of hydrogen.
The atmosphere of Venus extends to a height of 5500 km. In accordance with the rotation of Venus from the east to the West in the same direction, the atmosphere rotates. In accordance with the temperature profile, the atmosphere of Venus is divided into two areas: the troposphere and thermosphor. On the surface, the temperature is + 460 ° C, it changes little day and night. To the upper border of the troposphere, the temperature drops to -93 ° C.
Mars. The sky of this planet is not black, as it was assumed, but pink. It turned out that dust hanging in the air absorbs 40% of the incoming solar color, creating a color effect. Mars's atmosphere by 95% consists of carbon dioxide. About 4% falls on the share of nitrogen and argon. Oxygen and water vapor in the Martian atmosphere less than 1%. The average pressure of the atmosphere at the level of the surface is 15,000 times less than on Venus, and 160 times less than that of the earth's surface. The greenhouse effect lifts the average temperature at the surface at 9 ° C.
For Mars, sharp fluctuations in temperatures are characteristic: the temperature can reach + 27 ° C, but by morning to -50 ° C. This is due to the fact that the rarefied atmosphere of Mars is not able to retain heat. One of the manifestations of the temperature difference is very strong winds, the speed of which reaches 100 m / s. On Mars there are clouds of a wide variety of forms and species: Pirish, wavy.
A. Mikhailov, prof.
Science and life // illustration
Moon landscape.
Melting polar spots on Mars.
Orbits of Mars and Earth.
Mars Mars made up by Lowell.
Marsa model made by Külem.
Mars drawing made by Antoniadi.
Considering the issue of the existence of life on other planets, we will only talk about the planets of our solar system, since we do not know anything about the presence of other suns, which are stars, their own planetary systems like ours. According to modern views on the origin of the solar system, it is even possible to even believe that the education of the planets arising around the central star is the case, the probability of which is negligible, and that therefore the vast majority of the stars have no planetary systems.
Next, we must make a reservation that the question of life on the planets we intend to consider from our, earthly point of view, assuming that this life is manifested in the same forms as on earth, that is, assuming the vital processes and the overall structure of organisms like terrestrial. In this case, for the development of life on the surface of any planet, certain physicochemical conditions should exist, it should be not too high and not too low temperatures, it is necessary to have water and oxygen, the basis of the organic matter should be carbon compounds.
Atmosphere Planet
The presence of the planets atmosphere is determined by the voltage of gravity on their surface. Large planets have a sufficient strength of attraction to hold them like a gaseous shell. Indeed, the gas molecules are in constant fast movement, the speed of which is determined by the chemical nature of this gas and the temperature.
Light gases have the greatest speed - hydrogen and helium; With an increase in temperature, speed increases. Under normal conditions, i.e., the temperature of 0 ° and atmospheric pressure, the average speed of hydrogen molecule is 1840 m / s, and oxygen is 460 m / s. But under the influence of mutual collisions, individual molecules acquire speeds, which are several times greater than the specified average numbers. If a hydrogen molecule appears in the upper layers of the earth's atmosphere with a speed superior to 11 km / s, then such a molecule will fly away from the ground into the interplanetary space, since the power of earthly attraction will be insufficient for its retention.
The smaller the planet than it is less than massive, the less this limit or, as they say critical speed. For the Earth, the critical speed is 11 km / s, for Mercury it is only 3.6 km / s, for Mars 5 km / s, for Jupiter, the largest and most massive planets, - 60 km / s. It follows that Mercury, and even more less than the smaller body, as satellites of the planets (including our moon) and all small planets (asteroids), cannot keep the atmospheric shell in their surface with their weak attraction. Mars in a state, although with difficulty, hold the atmosphere, much more sparse than the Earth's atmosphere, as applies to Jupiter, Saturn, Uranus and Neptune, then their attraction is strong enough to hold powerful atmospheres containing light gases, like ammonia and methane, and possibly free hydrogen.
The absence of the atmosphere inevitably entails and lack of water in liquid state. In the airless space, water evaporation occurs much more vigorous than at atmospheric pressure; Therefore, water quickly appeals to the pair, which represents a very lightweight pelvis, exposed to the same participation as other atmospheric gases, i.e., it is more or less quickly leaving the surface of the planet.
It is clear that on the planet, deprived of the atmosphere and water, the conditions for the development of life are completely unfavorable, and we cannot expect on such a planet either a vegetable animal life. All small planets are falling under this category, satellites planets, and from large planets - Mercury. Let's say a little more about two bodies of this category, it is about Moon and Mercury.
Moon and Mercury
For these bodies, the lack of atmosphere is established not only by the above considerations, but also through direct observations. When the moon moves across the sky, making his way around the earth, she often closes his stars. The disappearance of the star behind the moon disk can be observed in a small pipe, and it always happens quite instantly. If the Lunar Paradise was surrounded by at least a rare atmosphere, then before well disappear, the star would shine through this atmosphere for some time, and the visible brightness of the star would be reduced, in addition, due to the refraction of light, the star would seem shifted from his place . All these phenomena are completely absent when coating the stars of the Luna.
The lunar landscapes observed in telescopes are striking the sharpness and contrast of their lighting. There is no half-one on the moon. Next to the bright, illuminated sun, there are deep black shadows. This happens because due to the absence of the atmosphere on the moon there is no blue day sky, which would soften the shadows with his light; Heaven there is always black. No on the moon and twilight, and after sunset, the dark night immediately comes.
Mercury is much further from us than the moon. Therefore, such details as on the moon, we can not observe on it. We are unknown appearance of his landscape. The coating of stars Mercury due to its visible smallness is an extremely rare phenomenon, and there is no indication that such coatings are ever observed. But there are passage of Mercury in front of the disk of the Sun, when we observe that this planet in the form of a tiny black point slowly carries over a bright solar surface. The land of Mercury is sharply outlined, and those phenomena that Venus seen in front of the sun, were not observed in Mercury. But it is possible that small traces of the atmosphere in Mercury are preserved, but this atmosphere has a completely insignificant density compared to earthly.
On the Moon and Mercury are completely unfavorable for life and temperature conditions. The moon revolves around his axis extremely slowly, thanks to which the day and night continue on it for fourteen days. Signless sunlight is not temperatified by air shell, and as a result, on the moon, the surface temperature rises to 120 °, i.e. above the water boiling point. During the same night, the temperature drops to 150 ° below zero.
During the lunar eclipse, it was observed, as for only an hour with a small temperature dropped from 70 ° heat to 80 ° frost, and after the end of the eclipse, almost equally returned to its initial value. This observation indicates an extremely small thermal conductivity of rocks forming the lunar surface. Solar heat does not penetrate deep into, but remains in the thinnest top layer.
It should be thought that the surface of the moon is covered with light and loose volcanic tuffs, maybe even ashes. Already at the depths of the meter, the contrasts of heat and cold are angry "Assessing, a mean temperature differs, little differ from the average temperature of the earth's surface, that is, the component of several degrees above zero. Being. Maybe there are some embryos of a live matter there, but the fate of them, of course, is unenviable.
On Mercury, the difference in temperature conditions is even more sharp. This planet is always turned to the Sun one side. On the daily hemisphere of Mercury, the temperature reaches 400 °, i.e. it is above the melting point of lead. And on the night hemisphere, the frost must reach the temperature of the liquid air, and if the atmosphere existed on Mercury, then on the night side it had to turn into a liquid, and it may even be frozen. Only on the border between day and night hemispheres within a narrow zone there may be temperature conditions, at least some favorable for life. However, there is no need to think about the possibility of a developed organic life. Further, in the presence of traces of the atmosphere, free oxygen could not be kept in it, since at the temperature of the day hemisphere oxygen, the oxygen is vigorously connected to most chemical elements.
So, in relation to the possibility of life on the Moon, perspectives are quite unfavorable.
Venus
Unlike Mercury, a certain signs of a thick atmosphere are observed on Venus. When Venus passes between the Sun and the Earth, it can be surrounded by a light ring, is her atmosphere, which is illuminated by the sun. Such a passage of Venus in front of the disk of the Sun is very rare: the last passage took place in 18S2, the nearest following will occur in 2004. However, almost annually, Venus passes although not through the solar disc, but it is close enough, and then it can be visible In the form of a very narrow sickle, like the moon immediately after the new moon. According to the laws of the prospects, the venera lighted by the Sun would have to be an arc of exactly 180 °, but in reality a longer light arc observes, which is due to the reflection and bending of the sunlight in the atmosphere of Venus. In other words, at Venus there are twilights that increase the duration of the day and partially illuminate its night hemisphere.
The composition of the atmosphere of Venus is still less studied. In 1932, with the help of spectral analysis, it found the presence of a large amount of carbon dioxide, corresponding to a layer with a capacity of 3 km under standard conditions (i.e., at 0 ° and 760 mm pressure).
The surface of Venus always seems to us dazzling white and without noticeable constant stains or outlines. It is believed that in the atmosphere of Venus is always a thick layer of white clouds, quite closing with a solid surface of the planet.
The composition of these clouds is unknown, but most likely that these are water vapors. What is under them, we do not see, but it is clear that the clouds must die in a kind of sunlight, which is closer to the Sun, which would be otherwise excessively strong.
Temperature measurements were given for daytime hemisphere about 50-60 ° heat, and for the night 20 ° frost. Such contrasts are explained by the slowness of Venus rotation near the axis. Although the exact period of its rotation is unknown due to the lack of noticeable spots on the surface of the planet, but, apparently, the day continues on Venus not less than our 15 days.
What are the chances of the existence of life on Venus?
In this regard, the molar of scientists diverge. Some believe that all oxygen in its atmosphere is chemically connected and exists only in carbon dioxide. Since this gas has low thermal conductivity, then in this case the temperature near the surface of Venus should be quite high, it may be even close to the boiling point of water. This could be explained by the presence in the upper layers of its atmosphere of a large number of water vapor.
Note that the above results of determining the temperature of Venus belong to the outer surface of the cloud cover, i.e. To a fairly high height above its solid surface. In any case, it is necessary to think that the conditions on Venus resemble a greenhouse or a greenhouse, but probably with even much higher temperature.
Mars
The Planet Mars is the greatest interest in terms of the issue of the existence of life. In many ways, he looks like Earth. On spots that are clearly visible on its surface, it has been established that Mars rotates around the axis, making one turnover in 24 hours and 37 m. Therefore, it has a change of day and night almost the same duration, as on earth.
The axis of rotation of Mars is with a plane of its orbit an angle of 66 °, almost exactly the same as the earth. Thanks to this inclination of the axis on Earth, the seasons change occurs. Obviously, on Mars there is the same shift, but only every time of the year on "EM almost twice as long as our. The reason for this is that Mars, being on average one and a half times farther from the Sun than the Earth, makes his turn around the sun in almost two Earth years, more precisely in 689 days.
The most distinctive details on the surface of Mars, noticeable when viewed by it in the telescope, is a white spot, according to its position coinciding with one of its poles. It is best to be visible a stain from the southern pole of Mars, because during the periods of its greatest intimacy to Earth Mars is inclined towards the sun and the earth with their southern hemispheres. It is noted that with the onset of winter in the appropriate hemisphere of Mars, the white spot begins to increase, and in the summer it decreases. There were even cases (for example, in 1894), when the polar spot in the fall almost completely disappeared. You can think that it is snow or ice, which is deposited in winter thin cover near the poles of the planet. That this cover is very thin, follows from the specified observation of the disappearance of the white spot.
Due to the remoteness of Mars from the Sun, the temperature on it is relatively low. Summer there is very cold, and nevertheless it happens that the polar snow is fully faced. The big duration of the summer does not compensate in sufficient, the lack of heat. It follows that snow falls there a little, perhaps only a few centimeters, it is even possible that white polar spots consist not from snow, but from Inea.
This circumstance is in complete agreement with the fact that in all data on Mars there is little moisture, little water. Seas and large water spaces are not found on it. In its atmosphere, clouds are very rarely observed. Orange painting of the surface of the planet itself, thanks to which the naked eye of Mars seems to be a red star (from where his name occurred by the name of the ancient Rod. Damn), most observers are explained by the fact that the surface of Mars is anhydrous sandy desert, painted iron oxides.
Mars moves around the sun according to a noticeably elongated ellipse. Due to this, his distance from the Sun is changing in fairly wide range - from 206 to 249 million km. When the Earth is on the same side of the Sun as Mars, the so-called confrontations of Mars occur (because Mars at this time is located in the side of the sky opposite to the Sun). During the confrontations of Mars is observed at the night sky in favorable conditions. The confrontations alternate on average after 780 days, or in two years and two months.
However, not in every opposition Mars approaches the Earth. It is your shortest distance. For this, it is necessary that the confrontation coincided with the time of the greatest approximation of Mars to the Sun, which is only every seventh or eighth opposition, i.e., about fifteen years. Such confrontations are called great confrontations; They took place in 1877, 1892, 1909 and 1924. The next great confrontation will be in 1939 tons. It is to these terms and the main observations of Mars and related discovery are timed. The closer to Earth Mars was during the confrontation of 1924, but then his distance from us was 55 million km. HA is a closer distance from the Earth Mars never happens.
"Channels" on Mars
In 1877, the Italian astronomer Skeparelli, producing observations into a relatively modest telescope, but under the transparent sky of Italy, discovered on the surface of Mars, except for dark spots, named, although incorrect seas, still a whole network of narrow straight lines or stripes that he Called the straits (in Italian Canale). Hence the word "channel" has become used in other languages \u200b\u200bto designate these mysteries.
Skiaparelli As a result of their perennial observations, he made a detailed map of the surface of Mars, on which hundreds of channels connecting between the Sobs\u003e Dark Spots "Seas" are applied. Later, American astronomer Lowell, built in Arizon, even a special observatory to observe Mars, discovered channels and on the dark spaces of the "Seas". He found that both the "seas" and the channels change their visibility depending on the seasons: in the summer they become darker, while taking a gray-greenish tint in the winter pale and become drowned. Lowell cards still Read more Card Skiaparelli, they cause many channels forming a complex, but rather correct geometric network.
To explain the phenomena of Lowell observed in Mars, developed the theory that has gained widespread, mainly among astronomy lovers. The theory of this is reduced to the following.
The orange surface of the planet Lowell, like most other observers, takes for a sandy empty. Dark spots of the "Seas", he believes as field covered with vegetation - fields and forests. Channels He considers the irrigation network carried out by reasonable beings living on the surface of the planet. However, the same channels are not visible from the ground, since their width is far from sufficient. To be visible from the ground, the channels must have a width of at least a tens of kilometers. Therefore, Lowell believes that we see only a wide lane of vegetation, which dissolves its green leaves when the canal itself, running in the middle of this strip, is filled with spring water flowing from the poles, where it is formed by the melting of polar snow.
However, there were no doubts about the reality of such rectilinear channels. The fact that observers armed with the most powerful modern telescopes were not seen, no channels were seen, and only observed an unusually rich picture of different parts and shades on the surface of Mars, deprived, however, the right geometric outlines. Only observers used by the instruments of the middle force were seen and sketched channels. From here there was a strong suspicion that the channels represent only the optical illusion (illusion), arising from the extreme enemy's tension. Many works and different experiments were conducted to clarify this circumstance.
The most convincing are the results obtained by the German physicist and physiologist Kühm. They were arranged a special model depicting Mars. On a dark background, Kule pasted a circle carved from an ordinary newspaper, at which several gray spots were placed, resembling their outlines of the Sea on Mars. If you consider such a model near, it is clear that it seems that it represents - you can read newspaper text and no illusion is created. But if you move away, then, with proper lighting, straight thin strips begin to appear, which comes from one dark spot to another and do not match the stricters of the printed text.
Cul investigated this phenomenon in detail.
He showed that the three standings of many small parts and shades, gradually moving one in another, when the eye cannot catch them "about all the details, a desire to combine these details of the simplest geometric schemes, as a result of which the illusion of straight strips appears where There are no correct outlines. The modern outstanding observer Antoniadi, who at the same time is a good artist, draws Mars Spotted, with a mass of incorrect parts, but without any rectilinear channels.
You might think that this question is best solved three help pictures. It is impossible to deceive the photographic plate: it should seem to show what is actually available on Mars. Unfortunately, this is not so. A photograph that in applied to the stars and the nebulae gave so much, with respect to the surface of the planets gives less than sees the eye of the observer in the same tool. This is explained by the fact that the image of Mars, obtained even with the help of the largest and long-focus tools, on the plate is very small sizes, - with a diameter "of everything. You are up to 2 mm. Of course, it is impossible to disassemble large details on this image. With a strong increase in such Photos performs a defect, from which modern lovers of photographs are suffering that, removing the instruments of the type "Watering". It is, the grain of the image that shares all the small details.
Life on Mars
However, the photos of Mars, shot through different light filters, with full clarity proved the existence of the atmosphere from Mars, although much more rarely than the earth. Sometimes in the evening in this atmosphere, light dots are noticed, which are likely to represent their cumulus clouds. But generally cloudy on Mars is insignificant, which is quite consistent with a small amount of water on it.
Currently, almost all Mars observers agree that the Dark Spots of the "Seas" really represent areas covered with plants. In this regard, Lowell's theory is confirmed. However, here to relatively recently there was one obstacle. The question has become complicated by the temperature conditions on the surface of Mars.
Since Mars is one and a half times further from the Sun than the Earth, he gets two with a quarter of times less heat. The question of how the temperature can warm its surface such a small amount of heat depends on the structure of the atmosphere of Mars, representing the "fur coat" of the thickness and composition of us.
Recently managed direct measurements to determine the temperature of the surface of Mars. It turned out that in the equatorial areas at noon, the temperature rises to 15-25 ° heat, but in the evening there comes a strong cooling, and the night, apparently, is accompanied by constant hard frosts.
The conditions on Mars are similar to those that are observed in our high mountains: affairs and transparency of air, significant heating with straight sunshine, cold in the shade and strong night frosts. Conditions, no doubt, are very severe, but it can be assumed that the plants are acclimatized, adapted to them, as well as to the lack of moisture.
So, the existence of plant life on Mars can be considered almost proven, but relative to animals, and even more reasonable, we can not say anything definite yet.
As for other planets of the Solar System - Jupiter, Saturn, Uranus and Neptune, it is difficult for them to assume the possibility of life on the following grounds: first, low temperature due to distance from the sun and, secondly, poisonous gases, recently open In their atmospheres, ammonia and methane. If these planets have a solid surface, then it is hidden somewhere at great depth, we see only the upper layers of their extremely powerful atmospheres.
It is even less likely to life on the most remote planet - recently open plutone, about whose physical conditions we still do not know anything.
So, of all the planets of our solar system (except for the Earth), it is possible to suspect the existence of life on Venus and consider almost proven life on Mars. But, of course, this all refers to the present time. Over time, with the evolution of planets, conditions can change greatly. We will not talk about this due to a lack of data.
The atmosphere of the planets and their satellites - the density and composition of it are determined by the diameter and mass of the planets, the distance from the Sun, the features of their formation and development. The further the planet is located from the Sun, the more volatile components included and is now included in its composition; The smaller the mass of the planet, the less its ability to hold these volatile, etc. Probably, the planets of the earth group have long lost their primary atmosphere. The nearest planet Mercury at its relatively low mass (not capable of keeping the molecule in the field with atomic weight less than 40) and the high temperature of the surface almost does not have an atmosphere (CO 2 \u003d 2000 atm-cm). There is some atmospheric crown consisting of inert gases - argon, neon and helium. Apparently, the argon and helium are radiogenic and constantly fall into the atmosphere due to the peculiar "enzymes" of rocks, allegations of Mercury, and possibly endogenous processes. The presence of neon is a riddle. It is difficult to assume that in the original substance Mercury could be attended so much neon so that he could still stand out from the depths of this planet, especially since this planet has no weight evidence of plutonic activity.
Venus has the warmest and powerful atmosphere of all planets of the earth. The atmosphere of the planet is 97% of CO 2, it found 0 2, N 2 and H 2 0. The surface at the surface reaches 747 + 20 K, pressure (8.83 + 0.15) 10 6 Pa. Venus's atmosphere - most likely the result of its internal activity. A. P. Vinogradov believed that the entire 2 atmosphere of Venus was due to the degassing of all carbonates at a high temperature of its surface. Apparently, this is not entirely so, because it is not clear how these carbonates could have been formed? It is unlikely that the surface temperature of Venus was in the past significantly lower, it was unlikely that its surface was once a hydrosphere, and, therefore, the carbonates could not form. It existed that all the water was lost by Venus, due to the dissociation of its molecules in the atmosphere on hydrogen and oxygen, followed by the dissipation of hydrogen into space. Oxygen entered into chemical reactions with a carbonaceous substance, which led to the enrichment of the atmosphere with carbon dioxide. It may be that, but then we must assume in Venus the presence of plutoism, providing the supply of all new portions of the substance from its depth to the reaction zone with oxygen, i.e. on the surface, which seems to be confirmed by the data obtained as a result Research "Venus-13" and "Venus-14".
On Mars there is a small atmosphere, the pressure of which at the base depending on the conditions is within (2.9-8.8) 10 2 pa. In the area of \u200b\u200bplanting station "Vi King-1", the atmosphere pressure was 7.6-10 2 Pa. The mass of the Martian atmosphere in the northern hemisphere is somewhat more than in South. In the atmosphere, small amounts of water vapors and ozone traces were found. The temperature of the surface of Mars varies depending on the latitude and on the border of the polar caps reaches 140-150 K. The temperature on the surface of the equatorial regions during the day can be 300 K, and at night it drops to 180 K. The maximum cooling occurs in high latitudes of Mars for a long polar night. When the temperature drops to 145 k, the condensation of atmospheric carbon dioxide begins, however, before this, water vapor extortes from the atmosphere. The polar caps of Mars consist, probably in the lower layer of water ice, which is covered on top of solid carbon dioxide.
The atmosphere of large planets of Jupiter, Saturn and uranium consist of hydrogen, helium, methane; Jupiter's atmosphere is the most powerful among other external planets. Based on the analysis of photo and infrared spectra, various models of light reflection in the atmospheres of the external planets, in addition to the prevailing H 2, CH 4, H 3 and not, such components are also detected as C 2 H 2, C 2 H 6, pH 3; The possibility of the presence of more complex organic substances is not excluded. The ratio N / N / NO -OPRO is 10, i.e. close to the solar, the ratio of hydrogen isotopes D / H, for example, for Jupiter is 2-10 ~ 5, which is close to the interstellar ratio, equal to 1.4-10 ~ 5. Based on the above, it can be concluded that the substance of the external planets does not have nuclear transformations and with the formation of the solar system, light gases were not removed from the atmosphere of external planets. . Everything is also noteworthy, such a phenomenon as the presence of an atmospheres from satellites of external planets. Even such satellites of Jupiter as IO and Europe, with the masses close to the mass of the moon, nevertheless have an atmosphere, and the satellite of the IO, in particular, is surrounded by a sodium cloud. The atmosphere of IO and Titanium have a reddish tint, while it is established that this color is caused by different compounds.
The atmosphere of the Earth is very different from the atmospheres of other planets of the solar system. Having a nitrogen-oxygen base, the earth's atmosphere creates conditions for life, which, due to certain circumstances, cannot be on other planets.
Instruction
Venus - the planet closest to the sun, which has an atmosphere, with such a high density that Mikhail Lomonosov in 1761 argued about its existence. The presence of the atmosphere in Venus is so obvious that, right up to the twentieth century, humanity was influenced by the illusion, as if the Earth and Venus are twin planets, and life is also possible on Venus.
Space studies have shown that everything is far from so rosy. The atmosphere of Venus on ninety-five percent consists of carbon dioxide, and does not release heat from the sun, creating a greenhouse effect. Because of this, the temperature on the surface of Venus is 500 degrees Celsius, and the likelihood of the existence of life on it is insignificant.
Mars has a similar composition with a venerera atmosphere, as well as consisting mainly of carbon dioxide, but with impurities of nitrogen, argon, oxygen and water vapor, however, in very small quantities. Despite the acceptable temperature of the surface of Mars at a certain time of the day, it is impossible to breathe such an atmosphere.
In defense of the supporters of ideas about life on other planets, it is worth noting that planetologists, examining the chemical composition of Mars breeds, in 2013 stated that 4 billion years ago on the red planet there was the same amount of oxygen as on earth.
Planets-giants do not have a solid surface, and their atmosphere in its composition is approximate to solar. Jupiter's atmosphere, for example, mainly consists of hydrogen and helium with a small amount of methane, hydrogen sulfide, ammonia and water, which is believed to be in the inner layers of this huge planet.
Saturn's atmosphere is very similar to Jupitorian, and also, for the most part, consists of hydrogen and helium, though in several other proportions. The density of such an atmosphere is extremely high, and we can only talk about its upper layers with a lot of accuracy, in which the clouds of frozen ammonia are floating, and the wind speed sometimes reaches one and a half thousand kilometers per hour.
Uranus, like the rest of the planets-giants, has an atmosphere consisting of hydrogen and helium. During the studies that were carried out with the help of Voyager devices, an interesting feature of this planet was opened: the atmosphere of uranium is not warmed by any internal sources of the planet, and it only gets energy from the sun. That is why uranium has the coldest atmosphere in the entire solar system.
Neptune has a gaseous atmosphere, but its blue color indicates that it has an unknown substance that gives an atmosphere from hydrogen and helium such a shade. Theories on the absorption of the red color of the atmosphere of methane, their full confirmation has not yet received.
What could be the connection between the presence on the planet of the atmosphere and the duration of its turnover around the axis? It would seem no. And yet on the example of the closest to the sun planet, Mercury, we are convinced that in some cases such a connection exists.
According to the strength of gravity on its surface, Mercury could hold the atmosphere of such a composition as earthly, although not so dense.
The rate required to complete overcoming the attraction of Mercury on its surface is equal to 4900 m / s, and this velocity at low temperatures do not reach the fastest of the molecules of our atmosphere). And nevertheless, Mercury is deprived of the atmosphere. The reason is that it moves around the sun like the movement of the moon near the Earth, that is, addressed to the central lumina, always the same and the same side. The time of climbing the orbit (88 days) is equal to the turnover time around the axis. Therefore, on one side of Mercury, the one that is always addressed to the Sun, - continuously lasts the day and stands the eternal summer; On the other side, dispersed from the Sun, a continuous night and eternal winter reign.
With such extraordinary climatic conditions, what should happen to the planet's atmosphere? Obviously, at night half under the influence of a terrible cold, the atmosphere thickens into the liquid and will frozen. Due to the sharp decrease in the atmospheric pressure there, the gas shell of the daily side of the planet rushes and hardens in turn. As a result, the entire atmosphere should gather on a hard side on the night side of the planet, or rather - in that part of it, where the sun does not look at all. Thus, the absence of an atmosphere in Mercury is an inevitable consequence of physical laws.
According to the same considerations, by which the existence of the atmosphere on Mercury is unacceptable, we must reject and guessed, often expressed that there is an atmosphere on the invisible side of the Moon. It is safe to argue that if there is no atmosphere on one side of the moon, it cannot be on the opposite). At this point, it is divided with the true fantastic novel of Wells "The first people on the moon." The novelist assumes that there is air on the moon, which in a solid 14-day night has time to thicken and climb, and with the onset of the day it turns into a gaseous state, forming an atmosphere. Nothing like it, however, can not happen. "If, - wrote about the prof. O. D. Wollyson, - on the dark side of the moon, the air hardens, then almost all the air should go to a light side in the dark and there also to climb. Under the influence of sunlight, the hard air should turn into a gas that will immediately switch to the dark side and there to harden ... There should be continuous air distillation, and nowhere and can never achieve any noticeable elasticity. "
It is even established that in the atmosphere, more precisely - in the stratosphere of Venus, a lot of carbon dioxide - ten thousand times more than in the earth's atmosphere.