Satellite of Saturn and Mercury. Natural satellites of the planets of the solar system

21.02.2022 -

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Do you have Mercury moons: description of the first planet from the Sun with a photo, features of the orbit, the history of the formation of the planet and moons in space, Hill's sphere.

You may have noticed that almost every planet in the solar system has satellites. And Jupiter has 67 of them! Even offended by all Pluto has five. What about the first planet from the Sun? How many moons does Mercury have, and do they even exist?

Does Mercury have moons

If satellites are a fairly common phenomenon, then why is this planet devoid of such happiness? To understand the reason, you need to understand the principles of the formation of the moons and see how this relates to the situation on Mercury.

Creation of natural moons

First of all, the satellite is able to use material from the circumplanetary disk for formation. Then all the fragments are gradually combined and create large bodies that are able to acquire a spherical shape. A similar scenario was followed by Jupiter, Uranus, Saturn and Neptune.

The second way is to attract. Large bodies are able to influence gravity and attract other objects to themselves. This could have happened to the Martian moons Phobos and Deimos, as well as small moons around the gas and ice giants. There is even an idea that Neptune's large moon Triton was previously considered a trans-Neptunian object.

And the last - a strong collision. At the time of the formation of the solar system, the planets and other objects tried to find their place and often collided. This would cause the planets to eject massive amounts of material into space. They think that this is how the Earth's Moon appeared about 4.5 billion years ago.

Hill sphere

Hill's sphere is the area around a celestial body that dominates the solar attraction. There is zero velocity at the outer edge. This line the object is not able to step over. To get the moon, you need to have an object within this zone.

That is, all bodies that are in the Hill sphere are subject to the influence of the planet. If they are outside the line, then they obey our star. This also applies to the Earth, which holds the Moon. But Mercury has no satellites. In fact, he is not able to capture or form his own moon. And there are several reasons for this.

Size and orbit

Mercury is the smallest planet in the solar system, which was not lucky enough to be the very first, so its gravity is simply not enough to keep its satellite. Moreover, if a large object passed into Hill's sphere, it would more likely fall under solar influence.

In addition, there is simply not enough material in the orbital path of the planet to create a moon. Perhaps the reason is stellar winds and condensation radii of light materials. At the time of formation of the system, elements like methane and hydrogen remained in the form of gas near the star, and heavy ones merged into terrestrial planets.

However, in the 1970s still hoped that there might be a satellite. Mariner 10 caught a huge amount of UV rays, hinting at a large object. But the radiation disappeared the next day. It turned out that the device caught signals from a distant star.

Unfortunately, Venus and Mercury have to spend a century alone, as they are the only planets in the solar system that do not have satellites. We were fortunate to be at an ideal distance and have a large Hill sphere. And let's give thanks to the mysterious object that crashed into us in the past and gave birth to the moon!

Saturn's satellite Titan is one of the most mysterious and interesting worlds located literally next door to us. In general, our solar system is so diverse and contains its own worlds so different from each other that here you can find the most bizarre conditions and phenomena. Lava lakes and water volcanoes, seas of methane and almost supersonic hurricanes - all this is literally in the neighborhood.

Our nearest neighbors are much more interesting than people think. And now you will learn about one of them - a satellite named Titan. This is an amazing place like no other.

Titan is a unique place that has no analogues in the solar system.

Titan is the largest satellite of Saturn and the second largest satellite in the solar system after Ganymede. It is larger than the Moon and even Mercury, which is an independent planet.
Titan is 80% heavier than the Moon, and in general its mass is 95% of the mass of all Saturn's moons.
Titan has a very dense atmosphere, which no other satellite can boast of, and not even every planet. For example, Mercury has practically no it, while Mars has a much rarer one. Even the earth's atmosphere is much inferior to it in density - the pressure at the surface there is 1.5 times greater than the earth's, and the thickness of the atmosphere is 10 times greater.
Titan's atmosphere is composed of methane and nitrogen and is completely opaque due to clouds in the upper layers. You can't see the surface through it.
On the surface of Titan, rivers flow and there are lakes and even seas. But they do not consist of water, but of liquid methane and ethane. That is, this satellite of Saturn is completely covered with hydrocarbons.
In 2005, the Huygens probe landed on Titan, which was delivered there by the . The probe not only took the first photographs of the surface during its descent, but also transmitted a recording of wind noise.
Titan does not have its own magnetic field.
The sky of Titan is yellow-orange.
Winds constantly blow on Titan and hurricanes often occur, especially rapid movement occurs in the upper atmosphere.
Rain on Titan from methane.
The temperature on the surface is about -180 degrees Celsius.
Under the surface of Titan there is an ocean of water with ammonia impurities. The surface is predominantly water ice.
Titan has cryovolcanoes that erupt with water and liquid hydrocarbons.
Titan is a promising place to search for extraterrestrial life, at least in the form of bacteria.
Titan is geologically active.

Such is the satellite of Saturn - bubbling, boiling and erupting, where instead of water there are mostly hydrocarbons, although water is also quite enough. So it is no coincidence that scientists suggest that some kind of primitive life may also arise there - all the components for this are there, and the conditions are quite comfortable, albeit not on the surface itself.

Titan, although not a planet, is the most Earth-like place in the solar system. The atmosphere, rivers, volcanoes, water - all this is there, although in a slightly different quality.

Discovery of Titan

Saturn's moon Titan was discovered on March 25, 1655 by Christian Huygens, a Dutch astronomer, mathematician and physicist. He had a homemade 57 mm telescope with a magnification of about 50x. Armed with it, Huygens observed the planets, and found a certain body near Saturn, which made a complete revolution around the planet in 16 days.

Until June, Huygens observed this strange object, until the rings of Saturn were at their smallest opening and began to interfere with observations. Then the scientist was convinced that it was a satellite of Saturn, and calculated the period of its revolution - 16 days and 4 hours. He called it simply - Saturni Luna, that is, "Moon of Saturn." After Galileo's discovery of the moons of Jupiter, this was the second discovery of a satellite near another planet using a telescope.

The satellite received its modern name when John Herschel in 1847 proposed that all the satellites of Saturn be named after the setters and brothers of the god Saturn, and by that time there were seven of them.

In 1907, Comas Sola, a Spanish astronomer, observed a phenomenon where the central part of his disk becomes brighter than the edges. This served as evidence of the presence of an atmosphere on Titan. In 1944, Gerard Kuiper, using a spectrometer, determined that its atmosphere contained methane.

Dimensions and orbit of Titan

The diameter of Titan is 5152 km, that is, 0.4 Earth. It is the second largest moon after Ganymede in the entire solar system. Before the flight, its diameter was considered 5550 km, that is, more than Ganymede, and Titan was considered a record holder. However, it turned out that the error was due to a very thick and opaque atmosphere, and the actual size of the satellite itself turned out to be somewhat smaller.

Titanium is 50% larger than the Moon and 80% heavier than the Moon. The force of gravity on it is 1/7 of the earth. It consists approximately equally of ice and rock. Approximately the same structure have, Callisto, Ganymede.

Titan is a rather large object, therefore it has a hot core and exhibits geological activity. However, the origin of this satellite is still unclear. It remains an open question whether it was captured by Saturn from the outside or immediately formed in orbit from a gas and dust cloud. Since it is very different from the other satellites of Saturn, leaving them only 5% of the mass, the capture theory may well be correct.

The orbital radius of Titan is 1,221,870 kilometers. It lies far beyond the outermost ring. Due to this distance from the planet, this satellite is perfectly visible even in a small telescope. It completes a complete revolution in 15 days, 22 hours and 41 minutes - Huygens was slightly mistaken in his calculations, although he calculated quite accurately with his simplest means of observation.

Atmosphere of Titan

What is remarkable about Titan is its chic atmosphere, which many terrestrial planets would envy, except perhaps Venus. Its thickness is 400 km, which is ten times greater than the earth's, and the pressure at the surface is 1.5 earth's atmospheres. Mars would be jealous!

This is how Titan saw Voyager

Powerful winds blow in the upper layers, strong hurricanes occur, but only a weak breeze is felt near the surface itself. The higher, the stronger the winds, they coincide with the direction of rotation of the satellite. Above 120 km, very strong turbulence. But at an altitude of 80 km, complete calm reigns - there is a certain calm zone where the wind from the lower regions does not penetrate, and storms located above. It is possible that at this height the multidirectional air currents compensate and extinguish each other, although the exact nature of this phenomenon has not yet been clarified.

On Titan it rains or snows from methane or ethane from methane and ethane clouds.

However, the composition of the air there is not at all encouraging - 95% nitrogen, and the rest is mostly methane. By the way, only on Earth and on Titan the atmosphere consists mainly of nitrogen! In the upper layers in methane, under the influence of the Sun, the process of photolysis occurs and smog is formed from hydrocarbons, which we see as a dense cloudy curtain. This prevents the surface of Titan from being seen.

The origin of such a vast atmosphere is still unclear, but the most plausible version is the active bombardment of Titan by comets at the dawn of formation, 4 billion years ago. When a comet collides with a surface rich in ammonia, a large amount of nitrogen is released under the influence of enormous pressure and temperature. Scientists have calculated the leakage of the atmosphere and concluded that the original atmosphere was 30 times heavier than the current one! And even now she is not even frail.

The sky of Titan is about the same color as in the picture.

The upper layers of the atmosphere are exposed to sunlight, ultraviolet and radiation. Therefore, processes of splitting of methane molecules into various hydrocarbon radicals and ions are constantly taking place there. Nitrogen ionization also occurs. As a result, these chemically active elements constantly form new organic compounds of nitrogen and carbon, including very complex ones. Just some kind of biofactory! It is these organic compounds that make Titan's atmosphere appear yellow.

According to calculations, all the methane in the atmosphere would theoretically be used up in 50 million years in this way. However, the satellite has existed for billions of years and the methane in its atmosphere does not decrease. This means that its reserves are replenished all the time, possibly due to volcanic activity. There are also theories that special bacteria can produce methane.

Surface of Titan

The surface of Titan cannot be seen, even being close to the satellite, not to mention terrestrial telescopes. Dense clouds in the upper atmosphere are to blame for everything. However, spacecraft have done some research at different wavelengths and have revealed a lot about what lies beneath the clouds.

Moreover, in 2005, the Huygens probe separated from the Cassini station and landed directly on the surface of Titan, transmitting the first true panoramic photographs. The descent through the thick atmosphere took more than two hours. Yes, and Cassini itself, over the years spent in orbit of Saturn, took many photographs of both the cloud cover of Titan and its surface in different ranges.

The mountains of Titan taken by the Huygens probe from a height of 10 km.

The surface of Titan is mostly flat, without strong drops. However, in some places there are real mountain ranges up to 1 kilometer high. A mountain with a height of 3337 meters was also discovered. Also on the surface of Titan there are many lakes of ethane, and even entire seas - for example, the Kraken Sea is comparable in area to the Caspian Sea. There are many ethane rivers or their channels. At the landing site of the Huygens probe, many rounded stones are visible - this is a consequence of the impact of liquid on them; in earthly rivers, stones are also gradually turned.

The stones at the landing site of the Huygens probe had a rounded shape.

Few craters have been found on the surface of Titan, only 7. The fact is that this satellite has a powerful atmosphere that saves from small meteorites. And if the big ones fall, then the crater quickly falls asleep with various precipitations, collapses, erodes ... In general, the weather does its job, and pretty quickly only a neat depression remains from the huge crater. Yes, and most of the surface of Tatan so far seems to be a white spot, only a small part of it has been studied.

One of the seas of Titan is the Sea of Ligei with an area of 100,000 square meters. km.

Along the equator, Titan is surrounded by a curious formation, which scientists at first mistook for a methane sea. However, it turned out that these are dunes made of hydrocarbon dust, which fell in the form of precipitation or was brought by the wind from other latitudes. These dunes are located in parallel and stretched for hundreds of kilometers.

Structure of Titan

All information about the internal structure of Titan is based on calculations and observations of various processes on it. Inside it is a solid silicate core with a diameter of 3400 km - it consists of ordinary rocks. Above it is a layer of very dense water ice. Then comes a layer of liquid water with an admixture of ammonia and another icy one - the actual surface of the satellite. The upper layer, in addition to ice, contains rocks and everything that falls in the form of precipitation.

Titan structure.

Saturn, with its powerful attraction, has a strong effect on Titan. Tidal forces "warp" it and cause the core to heat up and the different layers to move. Therefore, volcanic activity is also observed on Titan - cryovolcanoes were found there, which erupt not with lava, but with water and liquid hydrocarbons.

subsurface ocean

The most curious thing on Titan is the possible presence of a subsurface ocean - the same water layer that is located between the surface and the core. If it actually exists, then it completely covers the entire satellite. According to calculations, the water in it contains about 10% ammonia, which serves as an antifreeze and lowers the freezing point of water, so it should be in liquid form there. Also, the water may contain a certain amount of different salts, as in the earth's sea water.

According to data collected by Cassini, such a subsurface ocean must actually exist, but it is located at a depth of about 100 km from the surface. There is also evidence that the water contains large amounts of sodium, potassium and sulfur salts, and this water is very salty. Therefore, it is unlikely that any life is possible in it. However, this issue continues to excite scientists and is of great interest. This has made Titan a high priority for future exploration, as has Jupiter's moon Europa, which also has a subsurface ocean. Scientists really want to go deep and see what there is in these oceans, especially to look for any life forms.

Life on Titan

Although the subsurface ocean, most likely, is too salty and cruel place for the origin of life, however, scientists do not exclude that it can still be on this satellite. Titanium is extremely rich in hydrocarbons, and various chemical processes with their participation are constantly taking place there, new molecules of rather complex organic substances are constantly being formed. Therefore, the origin of the simplest life cannot be ruled out.

Despite the rather harsh conditions, this could well have happened in methane and ethane lakes. These liquids may well replace water, and their chemical aggressiveness is even lower than that of water, and proteins and nucleic acids can be even more stable than those of the earth.

In general, the conditions on Titan are similar to the conditions that were on Earth at the stage of its inception, except for extremely low temperatures. Therefore, what happened once on Earth may well happen there.

One curious phenomenon has been observed. There was a hypothesis that the simplest life forms on Titan could well feed on acetylene molecules, and breathe hydrogen, releasing methane. So - according to Cassini research, there is practically no acetylene near the surface of Titan, and hydrogen also disappears somewhere. This is a fact, but there is no explanation for it yet, and this may well be the result of the presence of certain microorganisms. It is also a fact that the atmosphere of Titan is constantly fed by methane, although the solar wind blows a lot of it into space. Cryovolcanoes are one of its sources, lakes and seas are another, or maybe microorganisms also take part in this? On Earth, after all, it was they who transformed the atmosphere and saturated it with oxygen. So all this is very interesting and awaits further research.

And yet - when the Sun becomes a red giant, and this will happen in 6 billion years, the Earth will die. But on Titan it will become warmer, and then this satellite will take over the baton of the Earth. Millions of years will pass, and not only the simplest, but also complex forms of life will be able to develop there.

Observation of Saturn's moon Titan

Observation of Titan does not cause difficulties. It is the brightest of Saturn's moons, but cannot be seen with the naked eye. But it is quite possible to see it with 7x50 binoculars, although it is not so easy - its brightness is about 9m.

With a telescope, even a 60 mm one, Titan is very easy to detect. In more powerful instruments, it is seen quite clearly at a great distance from Saturn. For example, not only Titan is clearly visible through the refractor, but some other, smaller satellites of Saturn, surrounding it like a swarm. Of course, you won't be able to see it in a small tool. This requires apertures greater than 200 mm. If there is a telescope with an aperture of 250-300 mm, then it is possible to observe the passage of Titan's shadow across the planet's disk.

The solar system formed about 4.6 billion years ago. A group of planets, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto, together with the Sun make up the Solar System.

The sun

The sun - the central body of the solar system - is a star, a huge ball of gas, in the center of which nuclear reactions take place. The bulk of the mass of the solar system is concentrated in the Sun - 99.8%. That is why the Sun holds by gravity all the objects of the solar system, the size of which is not less than sixty billion kilometers Samygin S.I. Concepts of modern natural science - Rostov-on-Don, Phoenix, 2008.

Very close to the Sun, four small planets circulate, consisting mainly of rocks and metals - Mercury, Venus, Earth and Mars. These planets are called terrestrial planets.

Between the terrestrial planets and the giant planets is the asteroid belt Sagan K.E. Space - M., 2000 .. A little further there are four large planets, consisting mainly of hydrogen and helium. The giant planets do not have a solid surface, but they have an exceptionally powerful atmosphere. Jupiter is the largest of them. Followed by Saturn, Uranus and Neptune. All giant planets have a large number of satellites, as well as rings.

The most recent planet in the solar system is Pluto, which in its physical properties is closer to the satellites of the giant planets. Beyond the orbit of Pluto, the so-called Kuiper belt, the second asteroid belt, has been discovered.

Mercury, the closest planet to the Sun in the solar system, has been a complete mystery to astronomers for a long time. The period of its rotation around the axis was not accurately measured. Due to the lack of satellites, the mass was not known exactly. Proximity to the Sun prevented observations of the surface.

Mercury

Mercury is one of the brightest objects in the sky. In brightness, it is second only to the Sun, Moon, Venus, Mars, Jupiter and the star Sirius. In accordance with Kepler's 3rd law, it has the shortest period of revolution around the Sun (88 Earth days). And the highest average orbital speed (48 km / s) Hoffman V.R. Concepts of modern natural science - M., 2003 ..

The mass of Mercury is equal to the mass of the Earth. The only planet with less mass is Pluto. In terms of diameter (4880 km, less than half of the earth), Mercury also stands in the penultimate place. But its density (5.5 g/cm3) is approximately equal to the density of the Earth. However, being much smaller than the Earth, Mercury experienced a slight compression under the influence of internal forces. Thus, according to calculations, the density of the planet before compression is 5.3 g/cm3 (for the Earth, this value is 4.5 g/cm3). Such a large uncompressed density, surpassing the density of any other planet or satellite, indicates that the internal structure of the planet is different from the structure of the Earth or the Moon Isaac A. Earth and space. From reality to hypothesis - M., 1999 ..

The large value of the uncompressed density of Mercury must be due to the presence of a large amount of metals. According to the most plausible theory, in the bowels of the planet there should be a core consisting of iron and nickel, the mass of which should be approximately 60% of the total mass. And the rest of the planet should consist mainly of silicates. The core diameter is 3500 km. Thus, it lies at a distance of about 700 km from the surface. Simplistically, you can imagine Mercury as a metal ball the size of the Moon, covered with a rocky 700 km crust.

One of the unexpected discoveries made by the American space mission "Mariner 10" was the detection of a magnetic field. Although it is approximately 1% of the Earth, it is just as significant for the planet. This discovery was unexpected due to the fact that it was previously believed that the inner part of the planet has a solid state, and, therefore, a magnetic field could not form. It is difficult to understand how such a small planet could store enough heat to keep the core in a liquid state. The most probable assumption is that the core of the planet contains a significant part of iron and sulfur compounds, which slow down the cooling of the planet and due to this, at least the iron-gray part of the core is in a liquid state Sagan K.E. Space - M., 2000 ..

The first data characterizing the planet from a close distance were obtained in March 1974 thanks to a spacecraft launched as part of the American space mission Mariner 10, which approached at a distance of 9500 km and photographed the surface at a resolution of 150 m.

Although the surface temperature of Mercury has already been determined on Earth, more accurate data have been obtained from close measurements. The temperature on the day side of the surface reaches 700 K, approximately the melting point of lead. However, after sunset, the temperature quickly drops to about 150 K, after which it cools more slowly to 100 K. Thus, the temperature difference on Mercury is about 600K, which is greater than on any other planet Sadokhin A.P. Concepts of modern natural science - M., Unity, 2006 ..

Mercury strongly resembles the Moon in appearance. It is covered with thousands of craters, the largest of which reach 1300 km in diameter. Also on the surface there are steep slopes that can exceed a kilometer in height and hundreds of kilometers in length, ridges and valleys. Some of the largest craters have rays like the craters Tycho and Copernicus on the Moon, and many of them have central peaks. Gorkov VL, Avdeev Yu.F. Space alphabet. Book about space - M., 1984 ..

Most of the relief objects on the surface of the planet were named after famous artists, composers and representatives of other professions who contributed to the development of culture. The largest craters are named Bach, Shakespeare, Tolstoy, Mozart, Goethe.

In 1992, astronomers discovered regions with high levels of radio wave reflection, similar in properties to those of reflection near the poles on Earth and Mars. It turned out that these areas contain ice in craters covered with shadow. And while the existence of such low temperatures was not unexpected, the mystery turned out to be the origin of this ice on a planet, the rest of which is exposed to high temperatures and is completely dry.

Distinctive features of Mercury - long escarpments, which sometimes cross craters, are evidence of compression. Obviously, the planet was shrinking, and cracks were going along the surface. And this process took place after most of the craters formed. If the standard crater chronology is correct for Mercury, then this shrinkage must have occurred during the first 500 million years of Mercury's history.

Almost every planet in our solar system has a satellite. Some have dozens of them, for example, Jupiter has 67 of them. Does Mercury have satellites? As strange as it may sound, he doesn't have them.

Moons in the solar system are not uncommon. Even the smallest planet Pluto has an attendant, but why then does Mercury have no satellites?

satellites

Our Moon has been accompanying the Earth for over a million years. According to scientists, it appeared after some cosmic body, the size of Mars, crashed into the planet. Earth's gravity kept its fragments in its orbit. Gradually, all the fragments formed a single object, which we observe every night. Thus, the Moon appeared at the Earth, accompanying it for many years.

According to the assumptions of astronomers, Mercury had satellites, but once a very long time ago. But they either fell under the influence of the gravity of the Sun, or fell to the surface of the planet.

Mars has two satellites: Phobos and Deimos. These are ordinary asteroids that are not able to overcome the gravity of the planet. The presence of two moons of the red planet is due to the close location of the asteroid belt. But there is no such accumulation of meteorites near Mercury, and very few of them fly past it.

Pluto also has satellites - these are, in particular, Nikta and Hydra, large ice blocks that were close to this planet and could not cope with gravity. If suddenly these objects would be next to the Sun, they would turn into comets and cease to exist.

Mercury has no satellites, and their appearance is not expected in the near future.

History reference

In the seventies, scientists suggested that Mercury had a satellite, the name of which they did not have time to come up with, since this opinion was erroneous. This conclusion was made after outgoing ultraviolet radiation was recorded thanks to the Mariner-10 equipment. Some scientists have suggested that such large doses of radiation can only come from the satellite of Mercury. Later it turned out that the reason for this was the influence of a distant star, and all assumptions about the presence of accompanying bodies turned out to be false.

first planet

Mercury is the first planet in the solar system. It is an atmospheric world with many craters. Until the moment when the Messenger device flew to the planet, little was known about it. Now astronomers know a lot about it. For many years, Mercury has been accompanied by only one satellite, and even that of earthly origin.

Ice is present on the first celestial body in the solar system. It was found in craters where the sun's rays do not fall. Organic matter was also discovered, which is necessary for the construction of all living things. Such discoveries suggested that there was once life here. Sulfur and many other elements found on Earth were found on the surface of the planet. Scientists are still puzzling over the discovery of large reserves of sulfur, because no other planet has it in such quantities.

artificial satellite

In 2011, a spacecraft entered orbit, which began to accompany the planet. Now you can safely answer the question of how many satellites Mercury has - one.

Thanks to the new accompaniment, astronomers managed to collect a lot of information about the planet. They know what the angle of inclination of the axes, the period of rotation, the size of the planet. The device sent pictures of the planet's surface taken from space. The satellite was able to take photographs of the northern polar region, including a giant depression, the southern region, thereby closing all the gaps in information about the planet.

For the first time, scientists managed to see the structure of the planet, to examine in detail its relief from a very close distance.

Flight around the planet

Mercury's satellite Messenger is constantly exposed to gravity from the Sun. As with vehicles flying around the Earth, the trajectory of the flight of the machine gradually changes. In particular, the minimum flight altitude is trying to go up, and the maximum one is decreasing. Due to such jumps, the operating conditions of the equipment deteriorate. In order to somehow correct the research processes, a systematic analysis of the flight is periodically carried out, the trajectory is calculated. According to the plan, the restructuring of the apparatus will be carried out once a Mercury year or once every 88 Earth days. The apocenter will rise three hundred kilometers with the first orbit, and with the second it will descend to two hundred kilometers.

The main task of Messenger is to take as many pictures of the planet as possible from different areas. And astronomers received a huge number of photos, each of which is unique.

natural satellites

As has been repeatedly mentioned above, Mercury has no natural satellites. For them to arise, it is necessary either to fall on the planet of a huge number of asteroids that would bounce off it and begin to fly in orbit, or to attract comets to themselves, holding them by gravity. Presumably, according to the second scenario, an escort appeared near Mars and some gas planets.

According to many scientists, Mercury cannot be accompanied because of its low gravitational force: it is not able to keep cosmic bodies in orbit. In addition, if a large asteroid entered the zone where the object could linger, then it would certainly fall under the influence of the Sun and simply dissolve.

Trying to find photos and names of Mercury's satellites, one can only find information about the artificial tracking of the planet, which was developed on Earth. This is how Mercury and Venus have to spend their lives in splendid isolation, flying around the Sun without an escort.

The planet Mercury is the smallest planet of the terrestrial group, the first from the Sun, the innermost and smallest planet in the solar system, revolving around the Sun in 88 days. The apparent magnitude of Mercury ranges from -2.0 to 5.5, but is not easy to see due to its very small angular distance from the Sun. Its radius is only 2439.7 ± 1.0 km, which is less than the radius of the moon Ganymede and the moon Titan. The mass of the planet is 3.3x1023 kg. The average density of the planet Mercury is quite high - 5.43 g / cm³, which is only slightly less than the density of the Earth. Considering that the Earth is larger in size, the value of the density of Mercury indicates an increased content of metals in its bowels. The free fall acceleration on Mercury is 3.70 m/s². The second space velocity is 4.3 km/s. The planet can never be seen in the dark night sky. The optimal time for observing the planet is the morning or evening periods of the maximum distance of Mercury from the Sun in the sky, which occur several times a year. Relatively little is known about the planet. In 1974-1975, only 40-45% of the surface was photographed. In January 2008, the MESSENGER interplanetary station flew past Mercury, which will enter orbit around the planet in 2011.

In its physical characteristics, Mercury resembles the Moon. It is dotted with many craters, the largest of which is named after the great German composer Beethoven, its diameter is 625 km. The planet has no natural satellites, but has a very rarefied atmosphere. The planet has a large iron core, which is the source of the magnetic field and, in its totality, is 0.1 of the earth's. Mercury's core makes up 70% of the planet's total volume. The temperature on the surface of Mercury ranges from 90 to 700 K (-180, 430 °C). Despite the smaller radius, the planet Mercury still surpasses in mass such satellites of the giant planets as Ganymede and Titan. Mercury moves around in a rather highly elongated elliptical orbit at an average distance of 57.91 million km. The inclination of the orbit to the plane of the ecliptic is 7 degrees. Mercury spends 87.97 days per orbit. The average speed of the planet in orbit is 48 km/s. In 2007, Jean-Luc Margot's group summarized five years of radar observations of Mercury, during which they noticed variations in the planet's rotation that were too large for a model with a solid core.

The proximity to the Sun and the rather slow rotation of the planet, as well as the absence of an atmosphere, lead to the fact that Mercury experiences the sharpest temperature drops in. The average temperature of its daytime surface is 623 K, the nighttime temperature is only 103 K. The minimum temperature on Mercury is 90 K, and the maximum reached at noon at "hot longitudes" is 700 K. Despite such conditions, there have recently been suggestions that that ice could exist on the surface of Mercury. Radar studies of the polar regions of the planet have shown the presence of a highly reflective substance there, the most likely candidate for which is ordinary water ice. Entering the surface of Mercury when comets hit it, the water evaporates and travels around the planet until it freezes in the polar regions at the bottom of deep craters, where the Sun never looks, and where ice can remain almost indefinitely.

On the surface of the planet, smooth rounded plains were discovered, which received the name of basins by their resemblance to the lunar "seas". The largest of them, Kaloris, has a diameter of 1300 km (the ocean of Storms on the Moon is 1800 km). The appearance of valleys is explained by intense volcanic activity, which coincided in time with the formation of the planet's surface. The planet Mercury is partially strewn with mountains, the height of the highest reaches 2–4 km. In some regions of the planet, valleys and craterless plains are visible on the surface. On Mercury, there is also an unusual detail of the relief - the scarp. This is a 2–3 km high protrusion separating two surface areas. It is believed that the scarps formed as shifts during the early compression of the planet.

The oldest evidence of the observation of the planet Mercury can be found in Sumerian cuneiform texts dating back to the third millennium BC. The planet is named after the god of the Roman pantheon Mercury, an analogue of the Greek Hermes and the Babylonian Naboo. The ancient Greeks of the time of Hesiod called Mercury. Until the 5th century BC the Greeks believed that Mercury, visible in the evening and morning sky, are two different objects. In ancient India, Mercury was called Buddha and Roginea. In Chinese, Japanese, Vietnamese and Korean, Mercury is called the Water Star (in accordance with the ideas of the "Five Elements". In Hebrew, the name of Mercury sounds like "Koha in Hama" ("Solar Planet").