The Sun, eight of the nine planets (except Mercury) and three of the sixty-three satellites have an atmosphere. Each atmosphere has its own special chemical composition and behavior called "weather". Atmospheres are divided into two groups: for terrestrial planets, the dense surface of the continents or the ocean determines the conditions at the lower boundary of the atmosphere, and for gas giants the atmosphere is almost bottomless.

About the planets separately:

1. Mercury has practically no atmosphere - only an extremely rarefied helium shell with the density of the earth's atmosphere at an altitude of 200 km. Probably, helium is formed during the decay of radioactive elements in the bowels of the planet. Mercury has a weak magnetic field and no satellites.

2. The atmosphere of Venus consists mainly of carbon dioxide(CO2) as well as not a large number nitrogen (N2) and water vapor (H2O). In the form of small impurities, hydrochloric acid(HCl) and hydrofluoric acid (HF). The pressure at the surface is 90 bar (as in the earth's seas at a depth of 900 m); the temperature is about 750 K over the entire surface both day and night. The reason for such a high temperature near the surface of Venus is that not quite accurately called the "greenhouse effect": the sun's rays pass relatively easily through the clouds of its atmosphere and heat the surface of the planet, but thermal infrared radiation the surface itself escapes through the atmosphere back into space with great difficulty.

3. The rarefied atmosphere of Mars consists of 95% carbon dioxide and 3% nitrogen. Water vapor, oxygen and argon are present in small quantities. The average pressure at the surface is 6 mbar (i.e., 0.6% of the earth's). At such a low pressure, there can be no liquid water. The average daily temperature is 240 K, and the maximum in summer at the equator reaches 290 K. Daily temperature fluctuations are about 100 K. Thus, the climate of Mars is the climate of a cold, dehydrated high-altitude desert.

4. A telescope on Jupiter shows cloud bands parallel to the equator; bright zones in them are interspersed with reddish belts. Probably, bright zones are areas of updrafts where the tops of ammonia clouds are visible; reddish belts are associated with downdrafts, the bright color of which is determined by ammonium hydrosulfate , as well as compounds of red phosphorus, sulfur, and organic polymers. In addition to hydrogen and helium, CH4, NH3, H2O, C2H2, C2H6, HCN, CO, CO2, PH3, and GeH4 have been spectroscopically detected in Jupiter's atmosphere.

5. In a telescope, the disk of Saturn does not look as spectacular as Jupiter: it has a brownish-orange color and weakly pronounced belts and zones. The reason is that the upper regions of its atmosphere are filled with light-scattering ammonia (NH3) fog. Saturn is farther from the Sun, therefore, the temperature of its upper atmosphere (90 K) is 35 K lower than that of Jupiter, and ammonia is in a condensed state. With depth, the temperature of the atmosphere increases by 1.2 K / km, so the cloud structure resembles that of Jupiter: under a cloud layer of ammonium hydrosulfate there is a layer of water clouds. In addition to hydrogen and helium, CH4, NH3, C2H2, C2H6, C3H4, C3H8, and PH3 have been spectroscopically detected in Saturn's atmosphere.

6. The atmosphere of Uranus contains mainly hydrogen, 12-15% helium and some other gases. The temperature of the atmosphere is about 50 K, although in the upper rarefied layers it rises to 750 K during the day and 100 K at night.

7. The Great Dark Spot was discovered in the atmosphere of Neptune and a complex system eddy currents.

8. Pluto has a highly elongated and inclined orbit; at perihelion, it approaches the Sun at 29.6 AU and recedes at aphelion at 49.3 AU. Pluto passed perihelion in 1989; from 1979 to 1999 it was closer to the Sun than Neptune. However, due to the large inclination of Pluto's orbit, its path never intersects with Neptune. The average surface temperature of Pluto is 50 K, it changes from aphelion to perihelion by 15 K, which is quite noticeable at such low temperatures. In particular, this leads to the appearance of a rarefied methane atmosphere during the period of the planet's passage of perihelion, but its pressure is 100,000 times less than the pressure of the earth's atmosphere. Pluto cannot hold the atmosphere for a long time, because it is smaller than the moon.

The article talks about which planet does not have an atmosphere, why an atmosphere is needed, how it arises, why some are deprived of it, and how it could be created artificially.

Start

Life on our planet would be impossible without an atmosphere. And the point is not only the oxygen that we breathe, by the way, it contains only a little more than 20%, but also the fact that it creates the pressure necessary for living beings and protects from solar radiation.

According to scientific definition, the atmosphere is gas envelope the planet that rotates with it. To put it simply, a huge accumulation of gas is constantly hanging above us, but we will not notice its weight in the same way as the Earth's gravity, because we were born in such conditions and got used to it. But not everyone celestial bodies lucky to have her. So which planet does not take into account we will not take into account, since it is still a satellite.

Mercury

Atmosphere of planets this type consists mainly of hydrogen, and the processes in it are very violent. What is worth only one atmospheric vortex, which has been observed for more than three hundred years - that same red spot in the lower part of the planet.

Saturn

Like all gas giants, Saturn is made up mostly of hydrogen. Winds do not subside on it, lightning flashes and even rare auroras are observed.

Uranus and Neptune

Both planets are hidden by a thick layer of clouds of hydrogen, methane and helium. Neptune, by the way, holds the record for wind speed on the surface - as much as 700 kilometers per hour!

Pluto

Remembering such a phenomenon as a planet without an atmosphere, it is difficult not to mention Pluto. Of course, it is far from Mercury: its gaseous shell is "only" 7 thousand times less dense than the earth's. But still it is the most distant and yet little-studied planet. Little is also known about it - only that methane is present in it.

How to create an atmosphere for life

The idea of ​​colonizing other planets haunts scientists from the very beginning And even more so about terraformation (creation on conditions without means of protection). All this is still at the level of hypotheses, but on the same Mars it is quite possible to create an atmosphere. This process is complex and multi-stage, but its main idea is as follows: to spray bacteria on the surface, which will produce even more carbon dioxide, the density of the gas shell will increase, and the temperature will rise. After that, the melting of the polar glaciers will begin, and due to the increase in pressure, the water will not evaporate without a trace. And then the rains will come, and the soil will become suitable for plants.

So we figured out which planet is practically devoid of an atmosphere.

The closest to the Sun and the smallest planet in the system, only 0.055% of the size of the Earth. 80% of its mass is the core. The surface is rocky, indented with craters and funnels. The atmosphere is very rarefied and consists of carbon dioxide. The temperature of the sunny side is +500°C, the reverse side is -120°C. gravity and magnetic field not on Mercury.

Venus

Venus has a very dense atmosphere of carbon dioxide. The surface temperature reaches 450°C, which is explained by the constant greenhouse effect, the pressure is about 90 atm. The size of Venus is 0.815 the size of the Earth. The core of the planet is made of iron. There is a small amount of water on the surface, as well as many methane seas. Venus has no satellites.

Planet Earth

The only planet in the universe where life exists. Almost 70% of the surface is covered with water. The atmosphere consists of a complex mixture of oxygen, nitrogen, carbon dioxide and inert gases. The gravity of the planet has an ideal value. If it were smaller, oxygen would be in, if it were larger, hydrogen would collect on the surface, and life could not exist.

If you increase the distance from the Earth to the Sun by 1%, the oceans will freeze, if you decrease by 5%, they will boil.

Mars

Due to the high content of iron oxide in the soil, Mars has a bright red color. Its size is 10 times smaller than the earth. The atmosphere is made up of carbon dioxide. The surface is covered with craters and extinct volcanoes, the highest of which is Olympus, its height is 21.2 km.

Jupiter

The largest of the planets in the solar system. Larger than the Earth 318 times. Consists of a mixture of helium and hydrogen. Inside, Jupiter is hot, and therefore vortex structures predominate in its atmosphere. It has 65 known satellites.

Saturn

The structure of the planet is similar to Jupiter, but above all, Saturn is known for its ring system. Saturn 95 times larger than the earth, but its density is the smallest among the solar system. Its density is equal to the density of water. It has 62 known satellites.

Uranus

Uranus is 14 times larger than Earth. It is unique in its rotation "on its side". The tilt of its axis of rotation is 98o. The core of Uranus is very cold, because it gives off all the heat into space. Has 27 satellites.

Neptune

Larger than the Earth 17 times. Emits a lot of heat. It shows low geological activity, on its surface there are geysers from. Has 13 satellites. The planet is accompanied by the so-called "Neptune Trojans", which are bodies of an asteroid nature.

The atmosphere of Neptune contains a large amount of methane, which gives it a characteristic blue color.

Features of the planets of the solar system

hallmark of the planets solar fact their rotation not only around the Sun, but also along its own axis. Also, all planets are warm to a greater or lesser extent.

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• Planets of the solar system

The solar system is a collection of cosmic bodies, the interaction between which is explained by the laws of gravity. The sun is the central object of the solar system. Being at different distances from the Sun, the planets rotate in almost the same plane, in the same direction along elliptical orbits. 4.57 billion years ago, the solar system was born as a result of powerful compression of a cloud of gas and dust.

The sun is a huge hot star, mostly composed of helium and hydrogen. Only 8 planets, 166 moons, 3 dwarf planets s. As well as billions of comets, minor planets, small meteoroids, space dust.

Polish scientist and astronomer Nicolaus Copernicus mid-sixteenth century described General characteristics and structure of the solar system. He changed the prevailing opinion at that time that the Earth was the center of the universe. He proved that the center is the Sun. The rest of the planets move around it along certain trajectories. The laws explaining the motion of the planets were formulated by Johannes Kepler in the 17th century. Isaac Newton, physicist and experimenter, substantiated the law of universal attraction. However, to study in detail basic properties and the characteristics of the planets and objects of the solar system could only in 1609. The great Galileo was telescope invented. This invention made it possible to observe the nature of planets and objects with one's own eyes. Galileo was able to prove that the sun rotates on its axis by observing the movement of sunspots.

The main characteristics of the planets

The weight of the Sun exceeds the mass of others by almost 750 times. The force of gravity of the Sun allows it to hold 8 planets around it. Their names are: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune. All of them revolve around the Sun along a certain trajectory. Each of the planets has its own system of satellites. Previously, another planet revolving around the Sun was Pluto. But modern scientists, based on new facts, have deprived Pluto of the status of a planet.

Jupiter is the largest of the 8 planets. Its diameter is approximately 142,800 km. This exceeds the diameter of the Earth by 11 times. The planets closest to the Sun are considered terrestrial or inner planets. These include Mercury, Venus, Earth and Mars. They, like the Earth, are composed of solid metals and silicates. This allows them to differ significantly from other planets located in the solar system.

The second type of planets are Jupiter, Saturn, Neptune and Uranus. They are called outer, or Jupiterian planets. These planets are giant planets. They consist mainly of molten hydrogen and helium.

Almost all planets in the solar system have satellites. About 90% of the satellites are concentrated mainly in orbits around the Jovian planets. The planets move around the Sun in certain trajectories. Additionally, they also rotate around their own axis.

Small objects in the solar system

The most numerous and smallest bodies in the solar system are asteroids. A whole belt of asteroids is located between Mars and Jupiter, consists of objects with a diameter of more than 1 km. Clusters of asteroids are also called the "asteroid belt". The flight path of some asteroids is very close to the Earth. The number of asteroids in the belt is up to several million. The largest body is the dwarf planet Ceres. This is a lump irregular shape with a diameter of 0.5-1 km.

Comets, consisting mainly of ice fragments, belong to a peculiar group of small bodies. From major planets and their companions, they are distinguished by their low weight. The diameter of the largest comets is only a few kilometers. But all comets have huge “tails” that are larger than the Sun in volume. When comets come close to the Sun, the ice evaporates and a dust cloud forms around the comet as a result of sublimation processes. The released dust particles under the pressure of the solar wind begin to glow.

Another space body is a meteor. As it enters Earth's orbit, it burns up, leaving a luminous trail in the sky. A variety of meteors are meteorites. These are larger meteors. Their trajectory sometimes passes close to the Earth's atmosphere. Due to the instability of the trajectory of movement, meteors can fall on the surface of our planet, forming craters.

One more objects solar system are centaurs. They are comet-like bodies, consisting of ice fragments of large diameter. According to their characteristics, structure and nature of movement, they are considered both comets and asteroids.

According to the latest scientific data, the solar system was formed as a result of gravitational collapse. As a result of powerful compression, a cloud was formed. Under the influence gravitational forces planets formed from particles of dust and gas. The solar system belongs to the galaxy Milky Way and removed from its center by about 25-35 thousand light years. Every second throughout the universe, systems of planets similar to the solar system are born. And very possibly they also have sentient beings like us.

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Those who continue to believe that the solar system includes nine planets are deeply mistaken. The thing is that in 2006 Pluto was expelled from the big nine and now belongs to the category of dwarf planets. There are eight ordinary ones, although the authorities of Illinois legislated in their state for Pluto the former status.

Instruction

After 2006, Mercury became the smallest planet. For scientists, it is of interest both because of the unusual relief in the form of jagged slopes that strewn the entire surface, and the period of rotation around its axis. It turns out that it is only a third less time full turn around the sun. This is due to the strong tidal effect of the star, which slowed down the natural rotation of Mercury.

Venus, the second farthest from the center of gravity, is famous for its "hotness" - the temperature of its atmosphere is even higher than that of the previous object. The effect is due to the greenhouse system present on it, which arose due to the increased density and the predominance of carbon dioxide.

The third planet - Earth - is the habitat of people, and so far it is the only one where the presence of life has been accurately recorded. She has something that the previous two do not have - a satellite called the Moon, which joined her shortly after the appearance, and this happened significant event about 4.5 billion years ago.

The most warlike sphere of the solar system can be called Mars: its color is red due to high percentage in the soil of iron oxide, geological activity ended just 2 million years ago, and two satellites were attracted by force from among the asteroids.

Fifth in distance from the Sun, but the first in size, Jupiter has unusual story. It is believed that he had all the makings of turning into a brown dwarf - a small star, because the smallest of this category exceeds it in diameter by only 30%. Larger than it is, Jupiter will no longer receive dimensions: if its mass increased, this would lead to an increase in density under the influence of gravity.

Saturn is the only one among all the others that has a noticeable disk - the Cassini belt, consisting of small objects and debris surrounding it. Like Jupiter, it belongs to the class of gas giants, but is significantly inferior in density not only to it, but also to terrestrial water. Despite its "gaseousness", Saturn has a real northern lights at one of its poles, and its atmosphere is raging with hurricanes and storms.

Next on the list, Uranus, like its neighbor Neptune, belongs to the category ice giants: its bowels contain the so-called "hot ice", which differs from the usual high temperature, but not turning into steam due to strong compression. In addition to the "cold" component, Uranus also has a number of rocks, as well as complex structure clouds.

Closes the list of Neptune, open very in an unusual way. Unlike other planets discovered by visual observation, that is, more complex optical devices, Neptune was not noticed immediately, but only due to the strange behavior of Uranus. Later, through complex calculations, the location of the mysterious object exerting influence on him was discovered.

Advice 4: Which planets in the solar system have an atmosphere

Earth's atmosphere is very different from the atmospheres of other planets in the solar system. Having a nitrogen-oxygen basis, the earth's atmosphere creates the conditions for life, which, due to certain circumstances, cannot exist on other planets.

Instruction

Venus is the closest planet to have an atmosphere, and high density that even Mikhail Lomonosov in 1761 claimed about its existence. The presence of an atmosphere on Venus is so obvious fact that until the twentieth century, humanity was under the influence of the illusion that the Earth and Venus are twin planets, and that life is also possible on Venus.

Space research has shown that things are far from rosy. The atmosphere of Venus is ninety-five percent carbon dioxide, and does not release heat from the Sun to the outside, creating a greenhouse effect. Because of this, the temperature on the surface of Venus is 500 degrees Celsius, and the likelihood of life on it is negligible.

Mars has an atmosphere similar in composition to Venus, also 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 in certain time day, it is impossible to breathe such an atmosphere.

In defense of supporters of ideas about life on other planets, it is worth noting that planetary scientists, having studied the chemical composition of the rocks of Mars, stated in 2013 that 4 billion years ago there was

Uranus, like the other giant planets, has an atmosphere consisting of hydrogen and helium. During the research that was carried out using the Voyager spacecraft, a interesting feature of this planet: the atmosphere of Uranus is not heated by any internal sources planets, and receives all energy only from the Sun. That is why Uranus has the coldest atmosphere in the entire solar system.

Neptune has a gaseous atmosphere, but its blue color suggests that it contains a yet unknown substance that gives the atmosphere of hydrogen and helium such a shade. Theories about the absorption of the red color of the atmosphere by methane have not yet received their full confirmation.

Advice 5: Which planet in the solar system has the most satellites

Start at scientific research Jupiter's satellites were laid back in the 17th century by the famous astronomer Galileo Galilei. He discovered the first four satellites. Thanks to the development of the space industry and the launch of interplanetary research stations, it became possible to discover small satellites of Jupiter. Currently, based on information from the NASA space laboratory, it is safe to talk about 67 satellites with confirmed orbits.

It is believed that the moons of Jupiter can be grouped into outer and inner. External objects include objects located at a considerable distance from the planet. The orbits of the inner ones are much closer.

Satellites with internal orbits, or as they are also called Jupiterian moons, are quite large bodies. Scientists have noticed that the arrangement of these moons is similar to the solar system, only in miniature. Jupiter in this case acts as if in the role of the Sun. External satellites differ from internal ones in their small size.

Among the most famous large satellites of Jupiter, one can note those that belong to the so-called Galilean satellites. These are Ganymede (dimensions in km - 5262.4,), Europe (3121.6 km), Io. as well as Calisto (4820, 6 km).

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The atmosphere is the gaseous shell of the planet, moving together with the planet in world space as a whole. Almost all the planets in our solar system have their own atmospheres, but only Earth's atmosphere can support life. In the atmospheres of planets there are aerosol particles: solid dust particles raised from the solid surface of the planet, liquid or solid particles resulting from condensation atmospheric gases, meteor dust. Let us consider in detail the composition and features of the atmospheres of the planets of the solar system.

Mercury. There are traces of an atmosphere on this planet: helium, argon, oxygen, carbon and xenon are recorded. The pressure of the atmosphere on the surface of Mercury is extremely small: it is two trillionth of the normal earth's atmospheric pressure. With such a rarefied atmosphere, the formation of winds and clouds is impossible in it, 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 across the disk of the Sun, noticed a thin iridescent rim that surrounded the planet. This is how the atmosphere of Venus was discovered. This atmosphere is extremely powerful: the pressure at the surface turned out to be 90 times greater than at the surface of the Earth. The atmosphere of Venus is 96.5% carbon dioxide. No more than 3% is accounted for by nitrogen. In addition, impurities of inert gases (first of all, argon) were found. the greenhouse effect in the atmosphere of Venus raises the temperature by 400 degrees!

The sky on Venus has a bright yellow-green hue. The foggy haze extends to a height of about 50 km. Further, up to a height of 70 km, clouds of small drops of sulfuric acid go. It is believed that it is formed from sulfur dioxide, the source of which may be volcanoes. The speed of rotation at the level of the upper boundary of the clouds is different than above the very surface of the planet. This means that a hurricane-force wind at a speed of 100-300 m/s is constantly blowing over the equator of Venus at an altitude of 60-70 km in the direction of the planet's motion. The uppermost layers of Venus's atmosphere are composed almost entirely of hydrogen.

The atmosphere of Venus extends up to an altitude of 5500 km. In accordance with the rotation of Venus from east to west, the atmosphere also rotates in the same direction. According to the temperature profile, the atmosphere of Venus is divided into two regions: the troposphere and the thermosphere. On the surface, the temperature is + 460 ° C, it changes little day and night. To the upper boundary of the troposphere, the temperature drops to -93°C.

Mars. The sky of this planet is not black, as it was supposed, but pink. It turned out that the dust hanging in the air absorbs 40% of the incoming sunny color, creating a color effect. The atmosphere of Mars is 95% carbon dioxide. About 4% is accounted for by nitrogen and argon. Oxygen and water vapor in the Martian atmosphere is less than 1%. The average atmospheric pressure at the surface level is 15,000 times less than on Venus, and 160 times less than at the Earth's surface. The greenhouse effect raises the average surface temperature by 9°C.

Mars is characterized by sharp fluctuations in temperature: during the day the temperature can reach +27°С, but by morning it can reach -50°С. 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, whose speed reaches 100 m/s. On Mars there are clouds of a wide variety of shapes and types: cirrus, wavy.

A. Mikhailov, prof.

Science and life // Illustrations

Lunar landscape.

Melting polar spot on Mars.

Orbits of Mars and Earth.

Lowell's map of Mars.

Kuhl's model of Mars.

Drawing of Mars by Antoniadi.

Considering the question 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, of their own planetary systems like ours. By modern views on the origin of the solar system, it can even be assumed that the formation of planets circulating around the central star is an event, the probability of which is negligible, and that therefore the vast majority of stars do not have their own planetary systems.

Further, we need to make a reservation that we involuntarily consider the question of life on planets from our earthly point of view, assuming that this life manifests itself in the same forms as on Earth, i.e., assuming life processes and the general structure of organisms similar to those of the earth. In this case, for the development of life on the surface of a planet, certain physico-chemical conditions must exist, there must be not too high and not too low temperature, the presence of water and oxygen is necessary, the basis organic matter must be carbon compounds.

planetary atmospheres

The presence of an atmosphere on planets is determined by the stress of gravity on their surface. Large planets have enough gravitational force to keep a gaseous shell around them. Indeed, gas molecules are in constant rapid motion, the speed of which is determined by chemical nature this gas and temperature.

Light gases - hydrogen and helium - have the highest speed; as the temperature rises, the speed increases. Under normal conditions, i.e., a temperature of 0 ° and atmospheric pressure, average speed hydrogen molecule is 1840 m/sec, and oxygen 460 m/sec. But under the influence of mutual collisions, individual molecules acquire velocities that are several times higher than the indicated average numbers. If a hydrogen molecule appears in the upper layers of the earth's atmosphere with a speed exceeding 11 km / s, then such a molecule will fly away from the Earth into interplanetary space, since the force gravity will not be enough to keep it.

How less planet the less massive it is, the less this limiting 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 of all planets, it is 60 km/s. It follows from this that Mercury, and even lesser bodies, like the satellites of the planets (including our Moon) and all small planets (asteroids), cannot keep the atmospheric shell near their surface with their weak attraction. Mars is able, albeit with difficulty, to hold an atmosphere much thinner than that of Earth, but as for Jupiter, Saturn, Uranus and Neptune, their attraction is strong enough to hold powerful atmospheres containing light gases, such as ammonia. and methane, and possibly also free hydrogen.

The absence of an atmosphere inevitably entails the absence of water in liquid state. In airless space, the evaporation of water occurs much more vigorously than at atmospheric pressure; therefore, water quickly turns into vapor, which is a very light basin, subject to the same fate as other gases of the atmosphere, i.e., it leaves the surface of the planet more or less quickly.

It is clear that on a planet devoid of atmosphere and water, the conditions for the development of life are completely unfavorable, and we cannot expect either plant or animal life on such a planet. All small planets, satellites of planets, and from large planets - Mercury fall under this category. Let us say a little more about the two bodies of this category, namely the Moon and Mercury.

Moon and Mercury

For these bodies, the absence of an atmosphere has been established not only by the above considerations, but also by direct observations. When the Moon moves across the sky, making its way around the Earth, it often covers the stars. The disappearance of a star behind the disk of the Moon can be observed even through a small tube, and it always happens quite instantly. If the lunar paradise were surrounded by at least a rare atmosphere, then, before completely disappearing, the star would shine for some time through this atmosphere, and the apparent brightness of the star would gradually decrease, in addition, due to the refraction of light, the star would seem displaced from its place . All these phenomena are completely absent when the stars are covered by the Moon.

Lunar landscapes observed through telescopes amaze with the sharpness and contrast of their illumination. There are no penumbra on the Moon. There are deep black shadows next to bright, sunlit places. This happens because, due to the absence of an atmosphere on the Moon, there is no blue daytime sky, which would soften the shadows with its light; the sky is always black. There is no twilight on the Moon, and after sunset, a dark night immediately sets in.

Mercury is farther from us than the Moon. Therefore, we cannot observe such details as on the Moon. We do not know the type of its landscape. The occultation of the stars by Mercury, due to its apparent smallness, is extremely a rare thing, and there is no indication that such coverages have ever been observed. But there are transits of Mercury in front of the solar disk, when we observe that this planet in the form of a tiny black dot slowly creeps over the bright solar surface. In this case, the edge of Mercury is sharply delineated, and those phenomena that were seen during the passage of Venus in front of the Sun were not observed in Mercury. But still it is possible that small footprints Mercury's atmospheres have been preserved, but this atmosphere has a very negligible density compared to Earth's.

On the Moon and Mercury, temperature conditions are completely unfavorable for life. The moon rotates extremely slowly around its axis, due to which day and night continue on it for fourteen days. The heat of the sun's rays is not moderated by the air envelope, and as a result, during the day on the Moon, the surface temperature rises to 120 °, i.e., above the boiling point of water. During the long night the temperature drops to 150° below zero.

During lunar eclipse it was observed how, in just over an hour, the temperature dropped from 70 ° warm to 80 ° below zero, and after the end of the eclipse, almost in the same short time, returned to its original value. This observation points to the extremely low thermal conductivity of the rocks that form the lunar surface. solar heat does not penetrate deep into, but remains in the thinnest upper layer.

One must think that the surface of the Moon is covered with light and loose volcanic tuffs, maybe even ash. Already at a depth of a meter, the contrasts of heat and cold are smoothed out “so much so that it is likely that an average temperature prevails there, which differs little from average temperature earth's surface, i.e., a component of several degrees above zero. It may be that some embryos of living matter have been preserved there, but their fate, of course, is unenviable.

On Mercury, the difference in temperature conditions is even sharper. This planet always faces the Sun on one side. On the daytime hemisphere of Mercury, the temperature reaches 400 °, i.e., it is above the melting point of lead. And on the night hemisphere, frost should reach the temperature of liquid air, and if there was an atmosphere on Mercury, then on the night side it should turn into liquid, and maybe even freeze. Only on the border between the day and night hemispheres within a narrow zone can there be temperature conditions that are at least somewhat favorable for life. However, about the possibility of a developed organic life do not have to think. Further, in the presence of traces of the atmosphere, free oxygen could not be retained in it, since at the temperature of the daytime hemisphere, oxygen vigorously combines with most chemical elements.

So, with regard to the possibility of life on the Moon, the prospects are rather unfavorable.

Venus

Unlike Mercury, Venus has certain signs of a thick atmosphere. When Venus passes between the Sun and the Earth, it is surrounded by a light ring - this is its atmosphere, which is illuminated by the Sun in the light. Such passages of Venus in front of the solar disk are very rare: the last passage took place in 18S2, the next one will occur in 2004. However, almost every year Venus passes, although not through the solar disk itself, but close enough to it, and then it is visible in the form of a very narrow sickle, like the moon immediately after the new moon. According to the laws of perspective, the crescent of Venus illuminated by the Sun should make an arc of exactly 180 °, but in reality a longer bright arc is observed, which occurs due to the reflection and bending of the sun's rays in the atmosphere of Venus. In other words, there is twilight on Venus, which increases the length of the day and partially illuminates its night hemisphere.

The composition of the atmosphere of Venus is still poorly understood. In 1932, with the help spectral analysis the presence of a large amount of carbon dioxide was found in it, corresponding to a layer 3 km thick under standard conditions (i.e., at 0° and 760 mm of pressure).

The surface of Venus always appears to us as dazzlingly white and without noticeable permanent spots or outlines. It is believed that in the atmosphere of Venus there is always a thick layer of white clouds, completely covering the solid surface of the planet.

The composition of these clouds is unknown, but most likely they are water vapor. What is under them, we do not see, but it is clear that the clouds must moderate the heat of the sun's rays, which on Venus, which is closer to the Sun than the Earth, would otherwise be excessively strong.

Temperature measurements gave about 50-60° heat for the day hemisphere, and 20° frost for the night. Such contrasts are explained by the slow rotation of Venus around the axis. Although the exact period of its rotation is unknown due to the absence of noticeable spots on the surface of the planet, but, apparently, a day lasts on Venus no less than our 15 days.

What are the chances of life on Venus?

Scholars differ on this point. Some believe that all the oxygen in its atmosphere is chemically bound and exists only as part of carbon dioxide. Since this gas has a low thermal conductivity, in this case the temperature near the surface of Venus should be quite high, perhaps even close to the boiling point of water. This could explain the presence of a large amount of water vapor in the upper layers of its atmosphere.

Note that the above results of determining the temperature of Venus refer to the outer surface of the cloud cover, i.e. to pretty high altitude over its hard surface. In any case, one must think that the conditions on Venus resemble a greenhouse or conservatory, but probably with a much higher temperature.

Mars

The greatest interest from the point of view of the question of the existence of life is the planet Mars. In many ways, it is similar to Earth. From the spots that are clearly visible on its surface, it has been established that Mars rotates about its axis, making one revolution in 24 hours and 37 meters. Therefore, there is a change of day and night on it of almost the same duration as on Earth.

The axis of rotation of Mars makes an angle of 66 ° with the plane of its orbit, almost exactly the same as that of the Earth. Due to this axial tilt on Earth, the seasons change. Obviously, on Mars there is the same change, but only every season on Earth is almost twice as long as ours. The reason for this is that Mars, being on average one and a half times farther from the Sun than the Earth, makes its revolution around the Sun almost two earth years, more precisely in 689 days.

The most distinct detail on the surface of Mars, noticeable when viewed through a telescope, is a white spot, which in its position coincides with one of its poles. The spot is best seen south pole Mars, because during periods of its closest proximity to the Earth, Mars is tilted towards the Sun and Earth with its southern hemisphere. It has been noticed that with the onset of winter in the corresponding hemisphere of Mars, the white spot begins to increase, and in summer it decreases. There were even cases (for example, in 1894) when the polar spot almost completely disappeared in autumn. It can be thought that this is snow or ice, which is deposited in winter as a thin cover near the poles of the planet. That this cover is very thin follows from the above observation of the disappearance of the white spot.

Due to the remoteness of Mars from the Sun, the temperature on it is relatively low. The summer there is very cold, and yet it happens that the polar snows completely melt. Long duration summer does not adequately compensate for the lack of heat. It follows from this that little snow falls there, perhaps only a few centimeters, it is even possible that the white polar spots do not consist of snow, but of hoarfrost.

This circumstance is in full agreement with the fact that, according to all data, there is little moisture on Mars, little water. Seas and large water spaces not found on it. Clouds are very rarely observed in its atmosphere. The very orange coloration of the planet's surface, due to which Mars appears to the naked eye as a red star (hence its name from the ancient Roman god of war), is explained by most "observers" by the fact that the surface of Mars is a waterless sandy desert, colored with iron oxides.

Mars moves around the Sun in a markedly elongated ellipse. Due to this, its distance from the Sun varies over a 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 oppositions of Mars occur (because Mars is at that time in the side of the sky, opposite to the sun). During oppositions, Mars is observed in the night sky under favorable conditions. Oppositions alternate on average after 780 days, or after two years and two months.

However, not in every opposition Mars approaches the Earth. shortest distance. To do this, it is necessary that the opposition coincides with the time of the closest approach of Mars to the Sun, which happens only every seventh or eighth opposition, that is, after about fifteen years. Such oppositions are called great oppositions; they took place in 1877, 1892, 1909 and 1924. The next great confrontation will be in 1939. It is to these dates that the main observations of Mars and related discoveries are timed. Mars was closest to the Earth during the opposition of 1924, but even then its distance from us was 55 million km. ha more close range Mars never comes from Earth.

Channels on Mars

In 1877, the Italian astronomer Schiaparelli, making observations with a relatively modest telescope, but under the transparent sky of Italy, discovered on the surface of Mars, in addition to dark spots, albeit incorrectly called seas, a whole network of narrow straight lines or stripes, which he called the straits (canale in Italian). Hence the word "channel" began to be used in other languages ​​to refer to these mysterious formations.

Schiaparelli, as a result of his many years of observations, compiled a detailed map of the surface of Mars, on which hundreds of channels were drawn connecting the dark spots of the "seas" between the subs. Later, the American astronomer Lowell, who even built a special observatory in Arizona to observe Mars, discovered channels in the dark spaces of the "seas". He found that both the "seas" and the channels change their visibility depending on the seasons: in summer they become darker, sometimes taking on a gray-greenish tint; in winter they turn pale and become brownish. Lowell's maps are even more detailed than Schiaparelli's maps, they are marked with many channels that form a complex, but fairly regular geometric network.

To explain the phenomena observed on Mars, Lowell developed a theory that received wide use, mainly among amateur astronomers. This theory boils down to the following.

The orange surface of the planet Lowell, like most other observers, takes for a sandy wasteland. He considers the dark spots of the "seas" to be areas covered with vegetation - fields and forests. He considers the canals to be an irrigation network carried out by intelligent beings living on the surface of the planet. However, the channels themselves are not visible to us from the Earth, since their width is far from sufficient for this. To be visible from Earth, the channels must be at least tens of kilometers wide. Therefore, Lowell thinks that we see only a wide strip of vegetation, which unfolds its green leaves, when the channel itself, which lies in the middle of this strip, is filled in spring with water flowing from the poles, where it is formed from the melting of polar snows.

However, little by little, doubts began to arise about the reality of such straightforward channels. The most indicative was the fact that observers armed with the most powerful modern telescopes did not see any channels, but only observed an unusually rich picture of different details and shades on the surface of Mars, which, however, were devoid of regular geometric outlines. Only observers who used tools medium strength, saw and sketched channels. Hence, a strong suspicion arose that the channels represent only an optical illusion (an optical illusion) that occurs with extreme eye strain. A lot of work and various experiments have been carried out to clarify this circumstance.

The most convincing are the results obtained by the German physicist and physiologist Kühl. They arranged a special model depicting Mars. Against a dark background, Kühl pasted a circle he had cut out of an ordinary newspaper, on which were placed several gray spots, reminiscent of the outlines of the "seas" on Mars. If we consider such a model close up, then it is clearly visible what it is - you can read newspaper text and no illusion is created. But if you move further away, then with the right lighting, straight thin stripes begin to appear, going from one dark spot to another and, moreover, not coinciding with lines of printed text.

Kuhl studied this phenomenon in detail.

He showed that three are the presence of many small details and shades, gradually turning into one another, when the eye cannot catch them “about all the details, there is a desire to combine these details with simpler ones. geometric patterns, as a result of which the illusion of straight stripes appears where there are no regular outlines. The modern outstanding observer Antoniadi, who at the same time is a good artist, paints Mars spotty, with a lot of irregular details, but without any rectilinear channels.

You might think that this issue is best solved by three photography assistance. A photographic plate cannot be deceived: it would seem that it should show what actually exists on Mars. Unfortunately, this is not so. Photography, which, when applied to stars and nebulae, has given so much, in relation to the surface of the planets, gives less than what the eye of the observer sees with the same instrument. This is explained by the fact that the image of Mars, obtained even with the help of the largest and longest-focus instruments, on the plate turns out to be very small in size - only up to 2 mm in diameter. Of course, it is impossible to make out large details on such an image. In photographs, there is a defect from which modern photography enthusiasts who shoot with Leica-type devices suffer so much. Namely, the graininess of the image appears, which obscures all the small details.

Life on Mars

However, photographs of Mars, taken through different light filters, clearly proved the existence of an atmosphere on Mars, although much rarer than that of the Earth. Sometimes in the evening in this atmosphere bright points are noticed, which, probably, are cumulus clouds. But in general, the cloudiness on Mars is negligible, which is quite consistent with the small amount of water on it.

Nearly all observers of Mars now agree that the dark patches of the "seas" do indeed represent areas covered with plants. In this respect, Lowell's theory is confirmed. However, until relatively recently, there was one obstacle. The question was complicated by the temperature conditions on the surface of Mars.

Since Mars is one and a half times farther from the Sun than the Earth, it receives two and a quarter times less heat. The question of to what temperature such an insignificant amount of heat can warm its surface depends on the structure of the Martian atmosphere, which is a “fur coat” of thickness and composition unknown to us.

Recently it was possible to determine the surface temperature of Mars by direct measurements. It turned out that in the equatorial regions at noon the temperature rises to 15-25°C, but in the evening a strong cooling sets in, and the night, apparently, is accompanied by constant hard frosts.

Conditions on Mars are similar to those we see on our planet. high mountains: rarefaction and transparency of the air, significant heating by direct sunbeams, cold in the shade and severe night frosts. The conditions are no doubt very harsh, but it can be assumed that the plants have acclimatized, adapted to them, as well as to the lack of moisture.

So the existence plant life on Mars can be considered almost proven, but with regard to animals, and even more intelligent ones, we can’t say anything definite yet.

As for the other planets of the solar system - Jupiter, Saturn, Uranus and Neptune, it is difficult to assume the possibility of life on them for the following reasons: firstly, low temperature due to the distance from the Sun and, secondly, poisonous gases recently discovered in their atmospheres - ammonia and methane. If these planets have a solid surface, then it is hidden somewhere at a great depth, while we see only the upper layers of their extremely powerful atmospheres.

Even less likely is life on the planet farthest from the Sun, the recently discovered Pluto, about whose physical conditions we still know nothing.

So, of all the planets in our solar system (except the Earth), one can suspect the existence of life on Venus and consider the existence of life on Mars almost proven. But, of course, this is all about the present. Over time, with the evolution of planets, conditions can change dramatically. We will not talk about this due to lack of data.