The moon is not the only satellite of the earth. Is the Moon the only (natural) satellite of the Earth? The only natural satellite of the earth

The physical conditions on the Moon, as on any other celestial body, are largely determined by its mass and size. The force of gravity on the surface of the Moon is six times less than on the surface of the Earth, so it is much easier for gas molecules to overcome gravity and fly into outer space than on Earth. This explains the absence of an atmosphere and hydrosphere on our natural satellite. Conditions on the surface of planetary bodies, which include the Moon, are also determined by the flow of energy coming from the Sun (or from the interior of the planet). The absence of an atmosphere on the Moon and the long duration of day and night (a lunar day is about 99 Earth days) lead to sharp temperature fluctuations on its surface: from +120°C at the subsolar point to -170°C at the diametrically opposite point. We are, of course, talking about the temperature of the surface material itself, the so-called regolith. The thermal conductivity of this finely divided substance is extremely low, which is why the lunar surface quickly heats up and quickly cools down during the lunar day, and at a depth of about a meter there are practically no daily temperature fluctuations. The main reason for the crushing of the surface rocks of the Moon is the fall of meteorites and other smaller bodies from outer space onto its surface. Due to the absence of an atmosphere, these bodies maintain a speed of about Tens of kilometers per second before hitting the lunar surface. The absence of a gas shell around the Moon also determines the special mechanical properties of regolith: the sticking together of individual particles (due to the absence of oxide films) into porous clusters. As described by astronauts who visited the Moon, and as photographs of the tracks of lunar rovers show, this substance is similar in its physical and chemical properties (particle size, strength, etc.) to wet sand. According to its relief, the lunar surface is divided into two types, as can be seen on the map of the Moon: continents, visible from the Earth as light areas, and seas, visible as darker areas. Note that there is not a drop of water in these seas.

These areas differ, as we now know, in appearance, geological history and chemical composition. The most typical form of lunar relief are craters of various sizes. The diameter of the largest craters is 200 km, and those crater-holes that are noticeable in panoramas of the lunar surface are several centimeters in diameter. The smallest craters are visible on individual particles of lunar soil (regolith) when examined under a microscope. The relief forms of the lunar seas are more diverse. Here we see shafts stretching for hundreds of kilometers on their surface, once covered with liquid lava that flooded ancient craters. On the outskirts of the seas, and in other parts of the lunar surface, cracks are noticeable along which the crust shifts. In this case, fault-type mountains are sometimes formed. Folded mountains, as typical of our planet, are not found on the Moon. All these landforms can be clearly seen when observing the Moon through a telescope. A good idea of ​​the lunar landscape is given by panoramas compiled on the basis of documentary photographs. Noteworthy are the smoothness of the outlines, the absence of pointed peaks, steep slopes, the poor color of the landscape and the presence of a fairly large number of stones and clods.

The absence of erosion and weathering processes on the Moon leads to the fact that its surface is a kind of geological reserve, where for millions and billions of years all the relief forms that have arisen during this time are preserved in an unknown form, in other words, the entire geological history of the Moon is recorded.

This circumstance helps in studying the geological past of the Earth, which interests us from the point of view of searching for mineral reserves formed on our planet in those distant eras of which no traces have been preserved in its relief. Soviet automatic stations "Luna" and American expeditions under the Apollo program delivered instruments to the Moon intended for taking samples of lunar soil and delivering it to Earth, as well as for conducting magnetometric, seismological, astrophysical and other studies, both at landing sites and along the route of movement of lunar rovers. Photography from spacecraft made it possible to obtain materials for compiling a complete map of the Moon, including the reverse side, invisible from Earth. Seismic studies have identified three types of moonquakes.

The first type is associated with the fall of meteorites on the Moon, the second is caused by falling sediments from spacecraft or specially produced explosions. The third is natural moonquakes, which occur, as on Earth, in seismically active areas located near crustal faults. Moonquakes are much weaker than earthquakes, but thanks to the high sensitivity of seismometers installed on the Moon, they were recorded in large numbers, i.e., several hundred. Detailed studies of the propagation of seismic waves made it possible to establish the following: the Moon’s crust is thicker than the Earth’s crust (from 50 to 100 km); there is a core that is in liquid form (diameter no more than 400 km); there is a mantle - an intermediate layer between the crust and the core. In the marine areas of the Moon, the surface is covered with rocks similar to terrestrial oceanic basalts, and in continental areas - with lighter and denser rocks. The main part of these rocks is silicon oxide (which is also typical for the Earth), followed by oxides of iron, aluminum, magnesium, calcium, etc. The mineralogical composition of lunar rocks is poorer than that of terrestrial rocks.

There are no minerals formed in the presence of water and oxygen. These facts indicate that there has never been a noticeable oxygen atmosphere or hydrosphere on the Moon. No organic compounds, microorganisms or other signs of life were found on the Moon. However, no compounds were found in lunar rocks that would be harmful to humans or animals and plants. Under terrestrial conditions, seeds and seedlings of plants planted in soil enriched with powdered lunar substance did not experience any inhibitory effects and developed normally, assimilating the microelements contained in this substance. American astronauts who had direct contact with lunar material in the cabin during the last expeditions did not even undergo any quarantine, which, for safety reasons, was carried out after the first flights to the Moon. Studies have shown that the age of individual samples of lunar rocks reaches 4 - 4.2 billion years, which is much greater than the age of the oldest rocks discovered on Earth.

planet earth space moon

There are good reasons to believe that humans will not only be able to survive on Jupiter's moon Europa, but will also find life already existing there. Europa is covered with a thick ice crust, but many scientists are inclined to believe that underneath there is a real ocean of liquid water. Additionally, Europa's solid inner core adds to the chances of having the right environment to support life, be it common microbes or perhaps even more complex organisms.

It is definitely worth studying Europe for the presence of conditions for the existence of life and life itself. After all, this will greatly increase the chances of possible colonization of this world. NASA wants to test whether Europa's water has some connection to the planet's core and whether this reaction produces heat and hydrogen, like we do on Earth. In turn, studying the various oxidizing agents that may be present in the planet's icy crust will indicate the level of oxygen produced, as well as how much of it is located closer to the ocean floor.

There are prerequisites to believe that NASA will closely study Europe and attempt to fly there by 2025. It is then that we will find out whether the theories associated with this icy satellite are true. In situ studies could also reveal the presence of active volcanoes beneath the icy surface, which in turn would also increase the chances of life on this moon. Indeed, thanks to these volcanoes, essential minerals can accumulate in the ocean.

Titanium

Even though Titan, one of Saturn's moons, lies on the outer edge of the solar system, this world is one of the most interesting places for humanity and perhaps one of the candidates for future colonization.

Of course, breathing here will require the use of special equipment (the atmosphere is unsuitable for us), but there is no need to use special pressure suits here. However, of course, you will still have to wear special protective clothing, since the temperature here is very low, often dropping to -179 degrees Celsius. The gravity on this satellite is slightly lower than the level of gravity on the Moon, which means walking on the surface will be relatively easy.

However, you will have to seriously think about how to grow crops and take care of issues of artificial lighting, since only 1/300 to 1/1000 of the Earth’s level of sunlight falls on Titan. Dense clouds are to blame, but they nevertheless protect the satellite from excessive levels of radiation.

There is no water on Titan, but there are entire oceans of liquid methane. In this regard, some scientists continue to debate whether life could have formed under such conditions. Regardless, there is a lot to explore on Titan. There are countless methane rivers and lakes and large mountains. Plus, the views must be absolutely stunning. Due to Titan's relative proximity to Saturn, the planet in the satellite's sky (depending on cloud cover) occupies up to one third of the sky.

Miranda

Although Uranus's largest moon is Titania, Miranda, the smallest of the planet's five moons, is most suitable for colonization. Miranda has several very deep canyons, deeper than the Grand Canyon on Earth. These locations could be ideal for landing and establishing a base that would be protected from the harsh external environment and especially from the radioactive particles produced by the magnetosphere of Uranus itself.

There is ice on Miranda. Astronomers and researchers estimate that it makes up about half the composition of this satellite. Like Europa, there is a possibility of water on the satellite, which is hidden under the ice cap. We don't know for sure, and we won't know until we get closer to Miranda. If there is still water on Miranda, then this would indicate serious geological activity on the satellite, since it is too far from the Sun and sunlight is not able to maintain water in liquid form here. Geological activity, in turn, would explain all this. While this is just a theory (and most likely unlikely), Miranda's close proximity to Uranus and its tidal forces may be causing this very geological activity.

Whether there is liquid water here or not, if we establish a colony on Miranda, the very low gravity of the satellite will allow us to descend into the deep canyons without fatal consequences. In general, there will also be something to do and explore here.

Enceladus

According to some researchers, Enceladus, one of Saturn's moons, not only could be an excellent place to colonize and observe the planet, but is also one of the most likely places to already support life.

Enceladus is covered in ice, but observations from space probes have shown geological activity on the moon and, in particular, geysers erupting from its surface. The Cassini spacecraft collected samples and determined the presence of liquid water, nitrogen and organic carbon. These elements, as well as the energy source that released them into space, are the important “building blocks of life.” So the next step for scientists will be to detect signs of more complex elements and perhaps organisms that may be lurking beneath Enceladus's icy surface.

The researchers believe that the best place to establish a colony would be in the areas near which these geysers have been spotted - huge cracks on the surface of the south pole ice cap. Quite unusual thermal activity has been observed here, equivalent to the operation of approximately 20 coal-fired power plants. In other words, there is a suitable source of heat for future colonists.

Enceladus has many craters and fissures just waiting to be explored. Unfortunately, the atmosphere of the satellite is very thin, and low gravity can create some problems in the development of this world.

Charon

NASA's New Horizons spacecraft returned stunning images of the dwarf planet and its largest moon Charon after its encounter with Pluto. These images have caused heated debate in the scientific community, which is now trying to determine whether this satellite is geologically active or not. It turned out that the surface of Charon (as well as Pluto) is much younger than previously thought.

Although there are cracks in Charon's surface, the moon appears to be quite effective at avoiding asteroid impacts as it has very few impact craters. The cracks and faults themselves are very similar to those left by the flow of hot lava. The same cracks have been found on the Moon and are an ideal place to establish a colony.

It is believed that Charon has a very thin atmosphere, which may also be an indicator of geological activity.

Mimas

Mimas is often called the "Death Star". It is possible that an ocean may be hidden under the ice cap of this satellite. And despite this moon's overall ominous appearance, it may actually be suitable for supporting life. Observations by the Cassini space probe showed that Mimas wobbles slightly in its orbit, which could indicate geological activity beneath its surface.

And although scientists are very careful in their assumptions, no other traces that would indicate the geological activity of the satellite were found. If an ocean is discovered on Mimas, then this moon should be one of the first to be considered as the most suitable candidate for establishing a colony here. Rough calculations indicate that the ocean may be hidden at a depth of about 24-29 kilometers below the surface.

If the unusual orbital behavior has nothing to do with the presence of liquid water under the surface of this satellite, then, most likely, it is all to do with its deformed core. And the strong gravitational pool of Saturn's rings is to blame for this. Be that as it may, the most obvious and most reliable way to find out what is happening here is to land on the surface and take the necessary measurements.

Triton

Images and data from the Voyager 2 spacecraft in August 1989 showed that the surface of Neptune's largest moon, Triton, is composed of rocks and nitrogen ice. In addition, the data hinted that there may be liquid water beneath the moon's surface.

Although Triton has an atmosphere, it is so thin that it is of no use on the surface of the satellite. Being here without a particularly protected spacesuit is like death. Triton's average surface temperature is -235 degrees Celsius, making it the coldest cosmic object in the known universe.

Nevertheless, Triton is very interesting for scientists. And one day they would like to get there, establish a base and carry out all the necessary scientific observations and research:

“Some areas of Triton's surface reflect light as if they were made of something hard and smooth, like metal. These areas are believed to contain dust, nitrogen gas and possibly water that seeps through the surface and freezes instantly as a result of the incredibly low temperatures."

In addition, scientists estimate that Triton formed around the same time and from the same material as Neptune, which is quite strange given the size of the satellite. It appears to have formed somewhere else in the solar system and was then pulled in by Neptune's gravity. Moreover, the satellite rotates in the direction opposite to its planet. Triton is the only satellite of the solar system that has this feature.

Ganymede

Jupiter's largest moon, Ganymede, as well as other space objects in our solar system, have been suspected of the presence of water beneath the surface. Compared to other ice-covered moons, Ganymede's surface is considered relatively thin and easy to drill into.

In addition, Ganymede is the only satellite in the Solar System that has its own magnetic field. Thanks to this, northern lights can be observed very often over its polar regions. In addition, there are suspicions that a liquid ocean may be hiding under the surface of Ganymede. The satellite has a rarefied atmosphere, which contains oxygen. And although it is extremely small to support life as we know it, the satellite has the potential for terraforming.

In 2012, it planned a space mission to Ganymede, as well as two other moons of Jupiter, Callisto and Europa. The launch is expected to take place in 2022. It will be possible to get to Ganymede 10 years later. Although all three moons are of great interest to scientists, Ganymede is believed to contain the most interesting features and is potentially suitable for colonization.

Callisto

Roughly the size of the planet Mercury, Jupiter's second-largest moon is Callisto, another moon that has been suggested to contain water beneath its icy surface. In addition, the satellite is considered a suitable candidate for future colonization.

Callisto's surface mainly consists of craters and ice fields. The satellite's atmosphere is a mixture of carbon dioxide. Scientists are already suggesting that the very thin atmosphere of the satellite is replenished with carbon dioxide escaping from under the surface. Previously obtained data indicated the possibility of the presence of oxygen in the atmosphere, but further observations did not confirm this information.

Since Callisto is at a safe distance from Jupiter, radiation from the planet will be relatively low. And the lack of geological activity makes the satellite's environment more stable for potential colonists. In other words, it is possible to build a colony here on the surface, and not under it, as in many cases with other satellites.

Moon

So we have come to the first potential colony that humanity will establish outside its planet. We are, of course, talking about our Moon. Many scientists are inclined to believe that a colony on our natural satellite will appear in the next decade, and soon after that the Moon will become the starting point for more distant space missions.

Chris McKay, a NASA astrobiologist, is among those who believe the Moon is the most likely site for the first human space colony. McKay is confident that further exploration of the Moon with a space mission after Apollo 17 did not continue solely due to considerations of the cost of this program. However, current technologies developed for use on Earth can also be very cost-effective for use in space and will significantly reduce the cost of both the launches themselves and construction on the lunar surface.

Despite the fact that NASA's biggest mission right now is landing a man on Mars, McKay is confident that this plan will not be realized until the first lunar base appears on the Moon, which will become the starting point for further missions to the Red Planet. Not only many states, but also many private companies are showing interest in the colonization of the Moon and are even preparing corresponding plans.

Brief information:
Radius: 1,738 km
Orbital semimajor axis: 384,400 km
Orbital period: 27.321661 days
Orbital eccentricity: 0,0549
Orbital inclination to the equator: 5,16
Surface temperature: from - 160° to +120° С
Day: 708 hours
Average distance to Earth: 384400 km

Moon- this is perhaps the only celestial body about which, since ancient times, no one had any doubts that it was moving around. Even with the naked eye, dark spots of various shapes are visible on the disk of the Moon, some resembling a face, some two people, and some a hare. These spots began to be called back in the 17th century. In those days, it was believed that there was water on the Moon, which means there should be seas and oceans, like on Earth. The Italian astronomer Giovanni Riccioli assigned them names that are still used today: , , , , , , , , , etc. The lighter areas of the lunar surface were considered dry land.

Already in 1753, the Croatian astronomer Ruđer Bošković proved that the Moon does not have a . When it covers a star, it disappears instantly, and if the Moon had an atmosphere, the star would fade gradually. It followed from this that there could be no liquid water on the surface of the Moon, since in the absence of atmospheric pressure it would immediately evaporate.

Galileo also discovered mountains on the Moon. Among them were real mountain ranges, which began to be given the names of the earth's mountains: the Alps, Apennines, Pyrenees, Carpathians, Caucasus. But there were also special mountains on the Moon - ring ones, they were called or circuses. The Greek word "krater" means "bowl." Gradually the name “circus” disappeared from the scene, but the term “crater” remained.

Riccioli proposed giving the craters the names of great scientists of ancient and modern times. This is how the craters Plato, Aristotle, Archimedes, Aristarchus, Eratosthenes, Hipparchus, Ptolemy, as well as Copernicus, Kepler, Tycho (Brage), Galileo appeared on the Moon. Riccioli did not forget himself. Along with these famous names, there are also those who cannot be found in any book on astronomy today, for example Autolycus, Langren, Theophilus. But then, in the 17th century, these scientists were known and remembered.

Maps of the Moon (top to bottom): visible hemisphere, eastern hemisphere at longitude 120°, western hemisphere at longitude 120°

After the Soviet automatic interplanetary stations of the series photographed the far side of the Moon, craters with the names of Russian scientists and space explorers were placed on its maps: Lomonosov, Tsiolkovsky, Gagarin, Korolev, Mendeleev, Kurchatov, Vernadsky, Kovalevskaya, Lebedev, Chebyshev, Pavlov, and from astronomers - Blazhko, Bredikhin, Belopolsky, Glazenap, Numerov, Parenago, Fesenkov, Tserasky, Sternberg.

Rotation of the Moon. The time the Moon rotates around its axis exactly corresponds to the sidereal month, for this reason the Moon always faces the same side to the surface of the Earth. This situation was established over billions of years of evolution of the Earth-Moon system under the influence of tides in the lunar crust caused by the Earth. Because the Earth is 81 times more massive than the Moon, its tides are about 20 times stronger than those that the Moon causes on our planet. True, there are no oceans on the Moon, but its crust is subject to tidal influences from the Earth, just as the Earth's crust experiences tides from the Moon and the Sun. Therefore, if in the distant past the Moon rotated faster, then over billions of years its rotation has slowed down.

Moon rotation diagram

Lunar eclipses. The moon during a total lunar eclipse has a reddish color. The ancient inhabitants of South America, the Incas, thought that the Moon turned red from illness and if she died, she would probably fall from the sky and fall.

The Normans imagined that the red wolf Mangarm again became bolder and attacked the Moon. The brave warriors, of course, understood that they could not harm the celestial predator, but, knowing that wolves cannot stand noise, they shouted, whistled, and beat drums. The noise attack sometimes continued for two or even three hours without a break.

Moon during a total lunar eclipse

Lunar eclipses always occur during a full moon, when the Earth is between the Moon and the Sun and they all line up in one row. The Earth, illuminated by the Sun, casts a shadow into space. In length, the shadow has the shape of a cone, stretching over a million kilometers; it is round across, and at a distance of 360 thousand kilometers from the Earth its diameter is 2.5 times greater than the lunar diameter. Thanks to this, the duration of the full phase sometimes reaches one and a half hours. But at the moment of a lunar eclipse, the Moon is not completely dark, but reddish. The reddening of the Moon occurs due to the scattering of sunlight in the Earth's atmosphere.

Geometry of a lunar eclipse

Depending on how close the Moon is to the orbital node at the hour of the eclipse, it can pass through the middle of the shadow cone, and the eclipse will be as long as possible, or it can pass through the edge of the shadow, and then we will see a partial lunar eclipse. The cone of the earth's shadow is surrounded by penumbra. Only a portion of the sun's rays that are not obscured by the Earth enter this region of space. That's why there are penumbral eclipses. They are also reported in astronomical calendars, but these eclipses are indistinguishable to the eye; only a camera and a photometer are able to note the darkening of the Moon during the penumbral phase or penumbral eclipse.

View of a lunar eclipse from the Moon

But to persistent observers, the sky finally revealed a great secret: in 6585.3 days, 28 lunar eclipses always occur throughout the Earth. In the next 18 years, 11 days and 8 hours (and this is the named number of days), all eclipses will repeat according to the same schedule. All that remains is to add 6585.3 days to the day of each eclipse. Thus Babylonian and Egyptian astronomers learned to predict eclipses through “repetition.” In Greek it is saros. Saros allows you to calculate eclipses 300 years in advance. When the Moon's orbital movement was well studied, astronomers learned to calculate not only the day of the eclipse, as was done using Saros, but also the exact time of its beginning.

Consecutive phases of a lunar eclipse

Columbus began to prepare for astronomical observations on the shore, but the natives, who met the sailors with caution, interfered with preliminary observations of the Sun and flatly refused to supply the strangers with food supplies. Then Columbus, after waiting a couple of days, announced that that same evening he would deprive the islanders of moonlight if they... Of course, when the eclipse began, the frightened Caribs were ready to give everything to the white man if only he would leave the Moon.

The theory of the formation of lunar craters. How were lunar craters formed? This question caused a long discussion. We are talking about the struggle between supporters of two hypotheses of the origin of lunar craters: volcanic and meteorite.

According to the volcanic hypothesis, which was put forward in the 80s. XVIII century German astronomer Johann Schröter, the craters arose as a result of enormous eruptions on the surface of the Moon. In 1824, his compatriot Franz von Gruithuisen proposed the meteorite theory, which explained the formation of craters by the fall of meteorites. In his opinion, with such impacts, the lunar surface is pushed through.

Only 113 years later, in 1937, the Russian student Kirill Petrovich Stanyukovich (future doctor of science and professor) proved that when meteorites strike at cosmic speeds, an explosion occurs, as a result of which not only the meteorite evaporates, but also part of the rocks at the impact site.

Scheme of impact crater formation

Moon phases. It is known that the moon changes its appearance. It itself does not emit light, so only its surface illuminated by the Sun is visible in the sky - the day side, which is equal to 0.073, that is, it reflects on average only 7.3% of the light rays of the Sun. The Moon sends 465,000 times less light to Earth than the Sun. Its magnitude at full moon is -12.5. Moving across the sky from west to east, the Moon changes its appearance - phase, due to a change in position relative to the Sun and Earth. There are four phases of the moon: new moon, first quarter, full moon and last quarter. Depending on the phases, the amount of light reflected by the Moon decreases much faster than the area of ​​the illuminated part of the Moon, so that when the Moon is at quarter and we see half of its disk bright, it sends us not 50%, but only 8% of the light from full moon.

On a new moon, the Moon cannot be seen even with a telescope. It is located in the same direction as the Sun (only above or below it), and is turned towards the Earth by the unlit hemisphere. In one or two days, when the Moon moves away from the Sun, a narrow crescent can be observed a few minutes before its sunset in the western sky against the background of the evening dawn. The first appearance of the crescent moon after the new moon was called “neomenia” (“new moon”) by the Greeks. This moment was considered by ancient peoples to be the beginning of the lunar month.

Moon phase chart

The Moon moves further and further to the left of the Sun. Its sickle grows every day, remaining convex to the right, towards the Sun. 7 days and 10 hours after the new moon, a phase called the first quarter begins. During this time, the Moon moved 90° away from the Sun. Now the sun's rays illuminate only the right half of the lunar disk. After sunset, the Moon is in the southern sky and sets around midnight. Continuing to move further and further east from the Sun, the Moon appears on the eastern side of the sky in the evening. She comes in after midnight, and every day it gets later and later.

When our satellite is in the direction opposite to the Sun (at an angular distance of 180° from it), the full moon occurs. The full moon shines all night. It rises in the evening and sets in the morning. After 14 days and 18 hours from the moment of the new moon, the Moon begins to approach the Sun from the right. The illuminated fraction of the lunar disk decreases. The Moon rises above the horizon later and later and by morning it no longer sets. The distance between the Moon and the Sun decreases from 180° to 90°. Again only half of the lunar disk becomes visible, but this is its left part. The last quarter is coming. And 22 days and 3 hours after the new moon, the last quarter moon rises around midnight and shines throughout the second half of the night. By sunrise it appears in the southern sky.

The width of the lunar crescent continues to decrease, and the Moon itself gradually approaches the Sun from the right (western) side. The pale sickle appears in the eastern sky in the morning, getting later every day. The ashen light of the night moon is visible again. The angular distance between the Moon and the Sun decreases from 90° to 0°. Finally, the Moon catches up with the Sun and becomes invisible again. The next new moon begins. The lunar month has ended. 29 days 12 hours 44 minutes 2.8 seconds passed, or almost 29.6 days.

Consecutive phases of the moon

The Moon's path across the sky passes not far from the ecliptic, so the full Moon rises from the horizon at sunset and approximately repeats the path it took six months before. In summer, the Sun rises high in the sky, but the full Moon does not move far from the horizon. In winter, the Sun stands low, and the Moon, on the contrary, rises high and illuminates the winter landscapes for a long time, giving the snow a blue tint.

Internal structure of the Moon. The density of the Moon is 3340 kg/m3 - the same as the Earth's mantle. This means that our satellite either does not have a dense iron core, or it is very small.
More detailed information about the internal structure of the Moon was obtained as a result of seismic experiments. They began to be carried out in 1969, after the American spacecraft landed on the Moon. Instruments of the next four expeditions " , And " formed a seismic network of four stations, which operated until October 1, 1977. It registered seismic tremors of three types: thermal (cracking of the outer edge of the Moon due to sudden temperature changes during the change of day and night); moonquakes in the lithosphere with a source at a depth of no more than 100 km; deep-focus moonquakes, the foci of which are located at depths from 700 to 1100 km (the energy source for them is lunar tides).

The total release of seismic energy on the Moon per year is approximately a billion times less than on Earth. This is not surprising, since tectonic activity on the Moon ended several billion years ago, and on our planet continues to this day.

Internal structure of the Moon

According to seismic data, the lunar mantle can be divided into three components: upper, middle and lower. The thickness of the upper mantle is about 400 km. In it, seismic velocities slightly decrease with depth. At depths of approximately 500-1000 km, seismic velocities remain largely constant. The lower mantle is located deeper than 1100 km, where seismic wave velocities increase.

One of the sensations of lunar exploration was the discovery of a thick crust 60-100 km thick. This indicates the existence in the past on the Moon of the so-called magma ocean, in the depths of which melting and formation of the crust took place during the first 100 million years of its evolution. We can conclude that the Moon and Earth had a similar origin. However, the tectonic regime of the Moon differs from the plate tectonic regime characteristic of the Earth. The melting basaltic magma goes to build up the lunar crust. That's why she's so fat.

Hypotheses of the origin of the Moon. The first hypothesis about the origin of our satellite was proposed in 1879 by the English astronomer and mathematician George Darwin, the son of the famous naturalist Charles Darwin. According to this hypothesis, the Moon once separated from the Earth, which was in a liquid state at that time. Studies of the evolution of the lunar orbit did indicate that the Moon was once much closer to the Earth than it is now.

Changing views on the Earth's past and criticism of Darwin's hypothesis by Russian geophysicist Vladimir Nikolaevich Lodochnikov forced scientists, starting in 1939, to look for other ways of the formation of the Moon. In 1962, American geophysicist Harold Urey suggested that the Earth captured the already formed Moon. However, in addition to the very low probability of such an event, the similarity in the composition of the Moon and the Earth’s mantle spoke against Urey’s hypothesis.
In the 60s Russian researcher Evgenia Leonidovna Ruskol, developing the ideas of her teacher, academician Otto Yulievich Schmidt, built a theory of the joint formation of the Earth and the Moon as a double planet from a cloud of preplanetary bodies that once surrounded the Sun. This theory was supported by many Western scientists.

There is also an “impact” theory of the formation of the Moon. According to this theory, the Moon was formed as a result of a catastrophic collision of the Earth in the distant past with a planet the size of Mars.

Diagram and artistic representation of the impact theory of the formation of the Moon

Ray structure of lunar craters. Since the first telescopic observations of the Moon, astronomers have noticed that light stripes, or rays, radiate strictly along radii from some lunar craters. The centers of light rays are the craters Copernicus, Kepler, Aristarchus. But the Tycho crater has the most powerful system of rays: some of its rays stretch for 2000 km.

What kind of light substance forms the rays of lunar craters? And where did it come from? In 1960, when the dispute about the origin of the lunar craters themselves had not yet been completed, Russian scientists Kirill Petrovich Stanyukovich and Vitaly Aleksandrovich Bronshten, both ardent supporters of the meteorite hypothesis of their formation, proposed the following explanation of the nature of ray systems.

Crater Tycho

But why are they light? The fact is that the rays consist of finely crushed matter, which is always lighter than dense matter of the same composition. This was established by the experiments of Professor Vsevolod Vasilyevich Sharonov and his colleagues. And when the first astronauts set foot on the surface of the Moon and took the substance of lunar rays for research, this hypothesis was confirmed.

Exploration of the Moon by spacecraft. Before spacecraft flights, nothing was known about the far side of the Moon and the composition of its interior, so it is not surprising that the first flight of a spacecraft above Earth orbit was directed towards the Moon. This honor belongs to the Soviet spacecraft, which was launched on January 2, 1958. In accordance with the flight program, a few days later it passed at a distance of 6,000 kilometers from the surface of the Moon. Later that year, in mid-September, a similar Luna series device reached the surface of the Earth's natural satellite.

Device "Luna-1"

In February 1966, the device delivered an automatic lunar station to the Moon, which made a soft landing and transmitted to Earth several panoramas of the nearby surface - a gloomy rocky desert. The control system ensured the orientation of the device, activation of the braking stage on command from the radar at an altitude of 75 kilometers above the surface of the Moon, and separation of the station from it immediately before the fall. Depreciation was provided by an inflatable rubber balloon. The mass of Luna-9 is about 1800 kilograms, the mass of the station is about 100 kilograms.

The next step in the Soviet lunar program was automatic stations , , designed to collect soil from the surface of the Moon and deliver its samples to Earth. Their mass was about 1900 kilograms. In addition to the braking propulsion system and the four-legged landing device, the stations included a soil intake device, a take-off rocket stage with a return vehicle for soil delivery. Flights took place in 1970, 1972 and 1976, and small amounts of soil were delivered to Earth.

Solved another problem , (1970, 1973). They delivered self-propelled vehicles to the Moon - lunar rovers, controlled from the Earth using a stereoscopic television image of the surface.

traveled about 10 kilometers in 10 months, - about 37 kilometers in 5 months. In addition to panoramic cameras, the lunar rovers were equipped with: a soil sampling device, a spectrometer for analyzing the chemical composition of the soil, and a path meter. The masses of the lunar rovers are 756 and 840 kg.

The spacecraft were designed to take images during the fall, from an altitude of about 1,600 kilometers to several hundred meters above the lunar surface. They were equipped with six television cameras. The devices crashed during landing, so the resulting images were transmitted immediately, without recording. During three successful flights, extensive materials were obtained to study the morphology of the lunar surface. The filming of Rangers marked the beginning of the American planetary photography program.

The design of the Ranger spacecraft is similar to the design of the first Mariner spacecraft, which were launched to Venus in 1962. However, the further construction of lunar spacecraft did not follow this path. To obtain detailed information about the lunar surface, other spacecraft were used -. These devices photographed the surface with high resolution from the orbits of artificial moon satellites.

Additionally, precise mapping of the gravitational field was carried out, while regional mass concentrations were identified (which is important both from a scientific point of view and for landing planning purposes) and a significant displacement of the Moon’s center of mass from the center of its figure was established. The fluxes of radiation and micrometeorites were also measured.

The Lunar Orbiter devices had a triaxial orientation system, their mass was about 390 kilograms. After completing the mapping, these vehicles crashed onto the lunar surface to stop the operation of their radio transmitters.

The flights of the Surveyor spacecraft, intended to obtain scientific data and engineering information (mechanical properties such as, for example, the bearing capacity of lunar soil), made a great contribution to the understanding of the nature of the Moon and to the preparation of the Apollo landings.

Automatic landings using a sequence of commands controlled by closed-loop radar were a major technical advance at the time. The Surveyors were launched using Atlas-Centauri rockets (the Atlas cryogenic upper stages were another technical success of the time) and placed into transfer orbits to the Moon. Landing maneuvers began 30 - 40 minutes before landing, the main braking engine was turned on by radar at a distance of about 100 kilometers from the landing point. The final stage (descent speed of about 5 m/s) was carried out after the end of the main engine operation and its release at an altitude of 7500 meters. The Surveyor's mass at launch was about 1 ton and at landing - 285 kilograms. The main braking engine was a solid-fuel rocket weighing about 4 tons. The spacecraft had a three-axis orientation system.

Surveyor 3 on the Moon

The manned Apollo spacecraft were next in the American lunar exploration program. In February 1966, Apollo was tested in an unmanned version. However, what happened on January 27, 1967 prevented the program from being successful. On this day, astronauts E. White, R. Guffey, and V. Grissom died in a flash fire during training on Earth. After investigating the reasons, the tests were resumed and became more complicated. In December 1968, “Apollo 8 (still without a lunar cabin) was launched into a selenocentric orbit with a subsequent return to the Earth’s atmosphere at the second escape velocity. It was a manned flight around the Moon. The photographs helped clarify the location of the future landing of people on the Moon. On July 16, Apollo 11 launched towards the Moon and on July 19 entered lunar orbit. On July 21, 1969, people landed on the Moon for the first time - American astronauts N. Armstrong and E. Aldrin, delivered there by the Apollo 11 spacecraft. The astronauts delivered several hundred kilograms of samples to Earth and carried out a number of studies on the Moon: measurements of heat flow, magnetic field, level of radiation, intensity and composition of the solar wind. It turned out that the heat flow from the interior of the Moon is approximately three times less than from the interior of the Earth. Residual magnetization was discovered in the rocks of the Moon, which indicates the existence of a magnetic field on the Moon in the past. This was an outstanding achievement in history. exploration of outer space - for the first time, a person reached the surface of another celestial body and stayed on it for more than two hours. Following the flight of the Apollo 11 spacecraft, six expeditions were sent to the Moon over the course of 3.5 years (“Apollo 12” - “Apollo -”). 17"), five of which were quite successful. On the Apollo 13 ship, due to an accident on board, the flight program had to be changed, and instead of landing on the Moon, it was flown around and returned to Earth. In total, 12 astronauts visited the Moon, some stayed on the Moon for several days, including up to 22 hours outside the cabin, and drove several tens of kilometers on a self-propelled vehicle. They carried out quite a large amount of scientific research, collecting over 380 kilograms of lunar soil samples, which were studied by laboratories in the USA and other countries. Work on the program of flights to the Moon was also carried out in the USSR, but for several reasons it was not completed.

Apollo 11 on the Moon

In the 1990s, two small robotic missions were sent to the Moon. For 71 days in 1994, the mission orbited the Moon, testing sensors for a space-based missile defense system and mapping the contours and color of the Moon. During the mission, the Aitken impact pit was discovered at the south pole - a hole in the Moon with a diameter of 2.6 thousand km and a depth of about 13 km. The impact was so strong that it apparently pierced the entire crust all the way to the mantle. The color data obtained by Clementine, combined with information from samples obtained by the Apollo missions, allows the creation of a map of regional composition - the first accurate "rock map" of the Moon. Finally, Clementine gave us a subtle hint that the solid dark regions near the Moon's south pole may contain water ice brought over millions of years by comet impacts.

Shortly after Clementine, the craft mapped the lunar surface from orbit during its 1998-1999 mission. These data, together with those obtained during the Clementine mission, gave scientists global compositional maps showing the complex structure of the Moon's crust. Lunar Prospector was also the first to map the surface magnetic fields of the Moon. The data shows that Descartes (the Apollo 16 landing site) is one of the strongest magnetic zones on the Moon, which explains surface measurements made by John Young in 1972. The mission also discovered vast reserves of hydrogen at both poles, adding to the debate about the nature of lunar ice.

Now humanity is preparing to return to the Moon. International missions to lunar orbit are underway and planned to produce common maps of unsurpassed quality. Soft landings on the Moon are planned, particularly in the mysterious polar regions, to obtain new images of the surface, study sediments and the unusual environment of these areas. Eventually humans will return to the moon. And this time the goal will not be to prove that we can do it (as was the case with Apollo), but to learn how to use the Moon to support new and expanding space capabilities. On the Moon, humanity will gain the skills necessary to live and work on other worlds. We are using this knowledge and technology to open up the solar system to human exploration.

Lunar colony through the eyes of an artist

By going to the Moon, we will be able to better understand the “workings” of the Universe and our own origins. The study of the Moon changed the understanding of the collision of solid bodies. This process, once considered rare and unusual, is now considered fundamental to the origin and evolution of planets. As we return to the Moon, we look forward to learning even more about our past and, just as importantly, getting a glimpse into our future.

Interesting Facts.

• The moon is depicted on the coats of arms and flags of the following countries: Laos, Mongolia, Palau, the Sami flag, the Shan flag (Myanmar). The moon in the form of a crescent is depicted on the flags and coats of arms of the following countries: Ottoman Empire, Turkey, Tunisia, Algeria, Mauritania, Azerbaijan, Uzbekistan, Pakistan, Turkish Republic of Northern Cyprus.
• For Muslims, once a year the birth of a new moon marks the beginning of the month of fasting - Ramadan.
• Everyone knows the first words spoken on the moon by Neil Armstrong, but no one knows about the last ones, they were spoken by Eugene Cernan on December 11, 1972: “America’s challenge today determined the fate of the people of tomorrow.”
• The diameter of the Moon is 3476 km and is almost equal to the width of Australia, and the total area of ​​the Moon is 4 times smaller than Europe.
• On the Moon you can jump 6 times higher than on Earth. This is because the gravity on the Moon is only 1/6 that of the Earth. However, don't think that you will actually jump that high on the Moon - you will be wearing a heavy protective suit.
• During an eclipse of the Sun, the shadow cast by the Moon travels up to two kilometers per second.