A favorite of poets, psychics, astrologers, mystics and fortune tellers, a symbol of dreams, a talisman of romantics - all this is our constant companion, the Moon. Kilograms of soil, thousands of experiments, six landings in the Apollo program alone - and still many secrets and mysteries. What do we know about the structure of the Moon? Where did we get the information from and how reliable is it? We will talk about the answer to these questions and briefly about the structure of the Moon in this article.
Familiar Stranger
Mentions of our night guest are found in the most ancient sources - the runic Vedas. In 1635, Galileo discovered craters and volcanoes on its surface and proved for the first time that we see only one side of it. In 1959, the Soviet satellite Luna 3 orbited the Moon and took pictures. In 1969, Apollo 11 landed and Neil Armstrong set foot on its surface. And in 2009, NASA announced the presence of water in Cabeus Crater. But what do we still know about the structure of the Moon?
It all started with a curiosity
It was the same Armstrong and Aldrin who installed a seismometer, a device for measuring tectonic activity, 20 meters from the ship. And the device immediately began to show multiple moonquakes. And although those first tremors turned out to be only echoes of the astronauts’ steps towards the ship, this device subsequently provided data on numerous tremors inside the Moon. This is how the myth that the internal structure of the Moon does not change was dispelled and geological activity on our satellite was confirmed.
General characteristics
For earthlings, the Moon is the brightest object in the sky after the Sun, its magnitude is 12.7 m. The Moon rotates around its axis and around the Earth, and the periods of these rotations are the same and equal to 29 days 12 hours and 44 minutes. That is why (libration effect) we always see one side of it.
The mass of the satellite is 81.3 times less than the mass of the Earth and is equal to 7.3477·10 22 kg. Average density 3.35 g/m2. cm. Gravity acceleration is 1.62 m/s², not 9.8, as on Earth. That is why, even if the Moon once had an atmosphere, it could not hold it - the force of attraction was not enough.
What is inside
The structural features of the Moon's shells have not been studied enough. After all, the soil was extracted from a depth of only 2.5 meters. All other data on the structure of the Moon were obtained by geophysical methods using seismographs.
It is known that its surface is covered with a mixture of dust and rocky debris - rigolite. Meteorites constantly falling on the moon loosen and mix this layer, and its thickness ranges from centimeters to tens of meters.
Below the dust layer is the crust, upper mantle (asthenosphere), middle mantle, lower mantle and core. The crust in different areas has different thicknesses - from 0 to 105 kilometers and consists of basalt.
The diameter of the mantle is 80% of the total diameter and it consists mainly of rocks: olivine pyroxene, schnitzel, melilite.
What about the core?
Its presence near the Moon was a complete surprise. After all, it was believed that the satellite inside had cooled down.
The core consists of two parts:
- The interior is hard, made of iron sulfide.
- The external one is liquid, made of iron and impurities of sulfur and nickel.
It makes up 2% of the satellite's mass and has a diameter of about 340 km. Around it there is a boundary molten layer of the lower mantle. Core temperature from 1300K to 1900K
But the center of mass is located 2 km from the geometric center.
What does it consist of?
Today, scientists have 385 kg at their disposal, part of which is stored in packed containers until new methods for studying it are invented. In the meantime, we know that it contains oxygen, iron, magnesium, silicon, titanium, calcium, aluminum, and very little silver and gold. In total, about a hundred minerals have been discovered on the Moon so far, compared to several thousand on Earth.
What is known for sure is that there is no organic matter in the lunar soil, not even non-biological organic compounds.
Or maybe everything is wrong?
However, many researchers are convinced that the inside of the Moon is hollow and even artificially created. Supporters of the hollow moon theory are not ufologists and science fiction writers, but world-famous scientists. And to support their point of view, they argue about numerous anomalies in the structure of the Moon.
For example, in 1969, NASA conducted an experiment and dropped a probe on the Moon. And the satellite “buzzed” like a bell and this lasted for about an hour. Since then, theories and myths about the empty Moon in the middle have only gained momentum.
And the movement of unidentified objects around our satellite is too often recorded. Maybe there is an unearthly civilization inside today that is watching us?
A few more questions
The moon still holds many mysteries for humanity today.
For example, where did the energy come from from the American complex that was left there and continued broadcasting for two years? Despite the fact that technologically its batteries were designed for only a year.
Or another question. Modern space satellites take pictures of the Earth with even car license plates clearly visible. But at the same time, we have a minimal number of images of the Moon and at the same time very low quality. What are space corporations hiding from ordinary people?
And what did Neil Armstrong and Edwin Aldrin really see on the Moon, if we accept the falsification of their landing as true?
Ministry of Education and Science of Ukraine
Donetsk secondary school of I-III levels No. 44
in astronomy
on the topic of: " Moon"
11th grade students
DOSH I-III Art. No. 44
Zhdanko Elizaveta
teacher: Maslennikova I.L.
Donetsk 2011
Introduction
THE MOON is the natural satellite of the Earth, its constant closest neighbor. It is the second brightest object in the earth's sky after the Sun and the fifth largest natural satellite of the planets in the solar system. The Moon is also the first and only celestial body, besides the Earth, visited by man. The average distance between the centers of the Earth and the Moon is 384,467 km. Even before the era of space exploration, astronomers knew that the Moon was an unusual body. Although it is not the largest satellite in the solar system, it is one of the largest in relation to its planet, Earth. The density of the Moon is only 3.3 times that of water, which is less than that of any of the terrestrial planets: the Earth itself, Mercury, Venus and Mars. This circumstance alone makes us think about unusual conditions for the formation of the Moon. Soil samples from the surface of the Moon made it possible to determine its chemical composition and age (4.1 billion years for the oldest samples), but this only further confused our understanding of the origin of the Moon.
1. Moon in mythology
The moon in Roman mythology is the goddess of night light. The moon had several sanctuaries, one together with the sun god. In Egyptian mythology, the moon goddess Tefnut and her sister Shu, one of the incarnations of the solar principle, were twins. In Indo-European and Baltic mythology, the motif of the month courting the sun and their wedding is widespread: after the wedding, the month leaves the sun, for which the thunder god takes revenge on him and cuts the month in half. In another mythology, the month, who lived in the sky with his wife the sun, came to earth to see how people lived. On earth, the month was chased by Hosedem (an evil female mythological creature). The moon, hastily returning to the sun, only half managed to enter its chum. The sun grabbed him by one half, and Hosedem by the other and began to pull him in different directions until they tore him in half. The sun then tried to revive the month, which was left without the left half and thus without a heart, tried to make a heart for it from coal, rocked it in a cradle (a shamanic way of resurrecting a person), but everything was in vain. Then the sun commanded the month that it should shine at night with its remaining half. In Armenian mythology, Lusin (“moon”), a young man asked his mother, who was holding the dough, for a bun. The angry mother slapped Lusin in the face, from which he flew into the sky. Traces of the test are still visible on his face. According to popular beliefs, the phases of the moon are associated with the cycles of the life of King Lusin: the new moon - with his youth, the full moon - with maturity; when the moon wanes and a crescent appears, Lusin becomes old, and then goes to heaven (dies). He returns from paradise reborn.
There are also myths about the origin of the moon from parts of the body (most often from the left and right eyes). Most peoples of the world have special Lunar myths that explain the appearance of spots on the moon, most often by the fact that there is a special person there (“moon man” or “moon woman”). Many peoples attach special importance to the moon deity, believing that it provides the necessary elements for all living things.
In many traditions (in particular, Greek), the Moon patronizes magic, witchcraft, and fortune telling.
2. Origin of the Moon
There are several theories to explain the formation of the Moon. One of the first theories that explains the process of formation of the Moon was J. Darwin's theory that the Moon was formed as a result of the action of centrifugal forces during the formation of the Earth. As a result of the action of these forces, part of the earth's crust was thrown into outer space. From this part the Moon was formed. Due to the fact that, as scientists believe, throughout the history of the Earth, our planet has never had a sufficient rotation speed to confirm this theory, this point of view on the process of formation of the Moon is currently considered outdated. Another theory, developed by the German scientist K. Weizsäcker, the Swedish scientist H. Alfven and the American scientist G. Urey, suggests that the Moon formed separately from the Earth, and was subsequently simply captured by the Earth's gravitational field. The probability of such an event is very low, and, in addition, in this case one would expect a greater difference between the earth and lunar rocks.
The third theory, formulated by Soviet scientists - O.Yu. Schmidt and his followers, explains that both the Earth and the Moon were formed from a single protoplanetary cloud and the process of their formation took place simultaneously. The probability of such an event is very low, and, in addition, in this case one would expect a greater difference between the earth and lunar rocks.
Although the above three theories of the formation of the Moon explain its origin, they all contain certain contradictions. The dominant theory of the formation of the Moon today is the theory of a giant collision of the proto-Earth with a celestial body the size of the planet Mars. In this case, the lighter substances of the outer layers of the Earth would have to break away from it and scatter in space, forming a ring of fragments around the Earth, while the core of the Earth, consisting of iron, would remain intact. Eventually, this ring of debris fused together to form the Moon. The giant impact theory explains why the Earth contains large amounts of iron, but the Moon has almost none. In addition, from the material that was supposed to turn into the Moon, as a result of this collision, many different gases were released - in particular oxygen.
Rice. 1. - Collision of the Earth with an object the size of Mars and
moon formation
3. Internal structure of the Moon
The density of the Moon does not change much with depth, i.e. unlike the Earth, there is no large concentration of masses in the center.
The Moon consists of a crust that is composed of igneous crystalline rocks - basalts, an upper mantle, a middle mantle, a lower mantle (asthenosphere) and a core. This structure is believed to have formed immediately after the formation of the Moon - 4.5 billion years ago. The thickness of the lunar crust is believed to be 50 km. The thickness of the upper mantle is about 250 km, and the middle is about 500 km, and its boundary with the lower mantle is located at a depth of about 1000 km. Moonquakes occur within the thickness of the lunar mantle, but unlike earthquakes, which are caused by the movement of tectonic plates, moonquakes are caused by the Earth's tidal forces. In the depths there is a hot core, partly molten. However, unlike the Earth's core, it contains almost no iron, so the Moon has no magnetic field.
4. Surface of the Moon
The atmosphere of our satellite is very thin. One of the sources of the lunar atmosphere are gases that are released from the lunar crust, such gases include radon gas. Another source of gases in the lunar atmosphere are gases released when the lunar surface is bombarded by micrometeorites and the solar wind. Due to the weak magnetic and gravitational field of the Moon, almost all gases from the atmosphere escape into outer space. Not being protected by the atmosphere, the surface of the Moon heats up to + 110 ° C during the day, and cools down to -120 ° C at night, however, as radio observations have shown, these huge temperature fluctuations penetrate only a few decimeters deep due to the extremely weak thermal conductivity of the surface layers. For the same reason, during total lunar eclipses, the heated surface quickly cools, although some places retain heat longer, probably due to high heat capacity (so-called “hot spots”). The sky above the Moon is always black, even during the day, because to scatter sunlight and create a blue sky, like on Earth, air is needed, which is not there. Sound waves do not travel in a vacuum, so there is complete silence on the Moon.
The entire lunar ball is covered with a loose layer of crushed rocks. This layer is called regolith. Regolith was formed as a result of meteorite bombardment of the lunar surface. Impact-explosive processes accompanying meteorite bombardment contribute to loosening and mixing of soil, while simultaneously sintering and compacting soil particles. The thickness of the regolith layer varies from 3 meters in areas of the lunar “oceans” to 20 m on the lunar plateaus. The lunar surface is also influenced by solar and galactic corpuscular radiation, as well as solar electromagnetic radiation. According to modern concepts, the Moon has been in tectonic rest for over 2-3 billion years and, apparently, there are no active internal factors that could significantly influence the conditions for the formation and existence of regolith. Therefore, the uniform action of external factors on the surface determined a similar structure and structure of the regolith throughout the lunar globe and generally averaged the physical and mechanical characteristics of the lunar soil. This has been confirmed by direct experiments carried out on the surface of the Moon. In terms of its granulometric and morphological characteristics, lunar regolith has no analogues among natural terrestrial formations, which, as a rule, are significantly more homogeneous. Regolith consists of 50-70% of fine dusty substance, and its larger particles are represented by fragments of local igneous rocks (basalts, gabbros, dolerites, anorthosites, norites, troctolites) and particles formed during meteorite impact reworking of the lunar surface (breccias, slags, agglutinates, glasses). Lunar rocks are depleted in iron, water and volatile components, and due to the influence of the solar wind, the regolith is saturated with neutral gases. Based on radioisotopes, it was established that some fragments on the surface of the regolith had been in the same place for tens and hundreds of millions of years.
5. Relief of the lunar surface
The surface of the Moon can be roughly divided into types: old mountainous terrain with a large number of volcanoes and relatively smooth and young lunar seas. The main feature of the far side of the Moon is its continental nature.
The dark areas of the surface that we can see from Earth on the surface of the Moon are what we call “oceans” and “seas.” Such names come from antiquity, when ancient astronomers thought that the Moon had seas and oceans, just like the Earth. In fact, these dark areas of the Moon's surface were formed as a result of volcanic eruptions and are filled with basalt, which is darker than the surrounding rocks. The main lunar seas are concentrated within the visible hemisphere, the largest of them being the Ocean of Storms. It is adjacent to the Sea of Rains from the northeast, the Sea of Humidity and the Sea of Clouds from the south. In the eastern half of the disk visible from the Earth, the Sea of Clarity, the Sea of Tranquility and the Sea of Abundance stretch in a chain from northwest to southeast. This chain is adjoined from the south by the Sea of Nectar, and from the northeast by the Sea of Crises. Relatively small seas are located on the border of the visible and reverse hemispheres - the Eastern Sea, the Mare Sea, the Smith Sea and the Southern Sea. On the far side of the Moon there is only one significant marine-type formation - the Sea of Moscow. On the surface of the lunar maria, under certain lighting conditions, sinuous elevations called swells are visible. The height of these mostly gentle hills does not exceed 100-300 meters, but their length can reach hundreds of kilometers. A probable theory for their formation is that they arose during the solidification of lava seas due to compression. On the lunar surface, several small marine-type formations, relatively isolated from large formations, are called “lakes.” Formations bordering the seas and protruding into continental areas are called “bays”. The seas differ from continental areas in the low reflectivity of their surface matter, flatter relief forms and a smaller number of large craters per unit area - on average, calculated per unit area, the number of craters on the continental surface is 30 times higher than the number of craters in the seas. The relief elements also include the lunar mountains. They are represented by mountain ranges bordering the shores of most seas, as well as numerous ring-shaped mountains called craters. Individual peaks and small mountain ranges located on the surface of some lunar maria are probably, in most cases, dilapidated sides of craters. It is noteworthy that on the Moon, unlike the Earth, there are almost no linear mountain ranges, such as the Himalayas, Andes and Cordillera on Earth.
Cratering is the most characteristic feature of the lunar relief. There are about half a million craters larger than 1 km in size. Due to the absence of an atmosphere, water and significant geological processes on the Moon, the lunar craters were virtually unchanged and even ancient craters were preserved on its surface. The largest lunar craters are located on the far side of the Moon, for example the Korolev, Mendeleev, Gershprung craters and many others. In comparison, the Copernicus crater with a diameter of 90 km, located on the visible side of the Moon, seems very small. Also on the border of the visible side of the Moon there are giant craters, such as Struve with a diameter of 255 km and Darwin with a diameter of 200 km.
Nowadays, more than 35,000 large and about 200,000 small details have been recorded on maps of the Moon.
Both internal forces and external influences took part in the formation of lunar relief forms. Calculations of the thermal history of the Moon show that soon after its formation, the interior was heated by radioactive heat and was largely melted, which led to intense volcanism on the surface. As a result, giant lava fields and a number of volcanic craters were formed, as well as numerous cracks, ledges and more. At the same time, a huge number of meteorites and asteroids fell on the surface of the Moon in the early stages - the remnants of a protoplanetary cloud, the explosions of which created craters - from microscopic holes to ring structures with a diameter of many tens, and possibly up to several hundred kilometers. Nowadays, meteorites fall on the Moon much less frequently; volcanism also largely ceased as the Moon used up a lot of thermal energy and radioactive elements were carried into the outer layers of the Moon. Residual volcanism is evidenced by the outflow of carbon-containing gases in lunar craters, spectrograms of which were first obtained by the Soviet astronomer N.A. Kozyrev.
6. Age of the Moon
By studying radioactive substances contained in lunar rocks, scientists were able to calculate the age of the Moon. For example, uranium slowly turns into lead. In a piece of uranium-238, half of the atoms turn into lead atoms in 4.5 billion years. Thus, by measuring the proportion of uranium and lead contained in a rock, its age can be calculated: the more lead, the older it is. The rocks on the Moon became solid about 4.4 billion years ago. The moon had apparently formed shortly before this; its most probable age is about 4.65 billion years. This is consistent with the age of the meteorites, as well as with estimates of the age of the Sun.
7. Moon phases
moon crust relief surface phase
The phases of the Moon arise due to changes in the relative positions of the Earth, Moon and Sun.
The visible edge of the Moon's disk is called the limb. The line dividing the parts of the Moon's disk illuminated and not illuminated by the Sun is called the terminator. The ratio of the area of the illuminated part of the visible disk of the Moon to its entire area is called the Moon phase. There are four main phases of the moon: new moon, first quarter, full moon and last quarter. When the Moon is between the Sun and the Earth, its Earth-facing side is dark and therefore almost invisible. This moment is called the new moon, because, starting from it, the Moon seems to be born and becomes visible more and more. A quarter of the way through its orbit, the Moon shows half of its disk illuminated; at the same time they say that it is in the first quarter. When the Moon passes halfway through its orbit, the entire side facing the Earth becomes visible - it enters the full moon phase. The Earth also goes through different phases when viewed from the Moon. The time interval between two successive identical phases of the Moon is called a synodic month; its duration is 29.53 days. The sidereal month, i.e. The time it takes the Moon to make one revolution around the Earth relative to the stars is 27.3 days.
8. Movement of the Moon
The apparent movement of the Moon against the background of stars is a consequence of the actual movement of the Moon around the Earth. During the sidereal month, the moon always moves among the stars in the same direction - from west to east, or in a straight motion. The visible path of the Moon in the sky is a non-closing curve, constantly changing its position among the stars of the zodiac constellations. The apparent movement of the Moon is accompanied by a continuous change in its appearance, characterized by the phase of the Moon.
The main influence on the movement of the Moon is exerted by the Earth, although the much more distant Sun also influences it. Therefore, explaining the movement of the Moon becomes one of the most difficult problems of celestial mechanics. The first acceptable theory was proposed by Isaac Newton in his Principia (1687), where the law of universal gravitation and the laws of motion were published. Newton not only took into account all the disturbances in the lunar orbit known at that time, but also predicted some of the effects. In the 20th century, they use the theory of the American mathematician J. Hill, on the basis of which the American astronomer E. Brown calculated (1919) mathematical series and compiled tables containing the latitude, longitude and parallax of the Moon. The actual motion of the Moon is quite complex, and many factors must be taken into account when calculating it, such as the oblateness of the Earth and the strong influence of the Sun, which pulls the Moon 2.2 times stronger than the Earth.
The Moon moves around the Earth at an average speed of 1.02 km/sec in a roughly elliptical orbit in the same direction in which the vast majority of other bodies in the Solar System move, that is, counterclockwise when looking at the Moon's orbit from the North Pole. The semimajor axis of the Moon's orbit, equal to the average distance between the centers of the Earth and the Moon, is 384,400 km (approximately 60 Earth radii). Due to the ellipticity of the orbit and disturbances, the distance to the Moon varies between 356,400 and 406,800 km.
The period of revolution of the Moon around the Earth, the so-called sidereal month, is 27.3 days, but is subject to slight fluctuations and a very small secular reduction. The Moon rotates around an axis inclined to the ecliptic plane at an angle of 88°28", with a period exactly equal to the sidereal month, as a result of which it always faces the Earth with the same side.
9. Lunar eclipses
During a total lunar eclipse, the Moon completely moves into the Earth's shadow. The total phase of a lunar eclipse lasts much longer than the total phase of a solar eclipse. The shape of the edge of the earth's shadow during lunar eclipses served the ancient Greek philosopher and scientist Aristotle as one of the strongest proofs of the sphericity of the Earth. Philosophers of Ancient Greece calculated that the Earth was about three times larger than the Moon, simply based on the duration of eclipses (the exact value of this coefficient is 3.66). The Moon at the moment of a total lunar eclipse is actually deprived of sunlight, so a total lunar eclipse is visible from anywhere in the Earth's hemisphere. The eclipse begins and ends simultaneously for all geographic locations. However, the local time of this phenomenon will be different. Since the Moon moves from west to east, the left edge of the Moon enters the earth's shadow first. An eclipse can be total or partial, depending on whether the Moon enters the Earth's shadow completely or passes near its edge. The closer to the lunar node a lunar eclipse occurs, the greater its phase. Finally, when the disk of the Moon is covered not by a shadow, but by a penumbra, penumbral eclipses occur. It is difficult to notice them with the naked eye. During an eclipse, the Moon hides in the shadow of the Earth and, it would seem, should disappear from view every time, because The earth is opaque. However, the earth's atmosphere scatters the sun's rays, which fall on the eclipsed surface of the Moon "bypassing" the Earth. The reddish color of the disk is due to the fact that red and orange rays pass through the atmosphere best. Each lunar eclipse is different in the distribution of brightness and color in the Earth's shadow. The color of the eclipsed Moon is often assessed using a special scale proposed by the French astronomer André Danjon:
0 points - the eclipse is very dark, in the middle of the eclipse the Moon is almost or not visible at all.
1 point - the eclipse is dark, gray, details of the lunar surface are completely invisible.
2 points - the eclipse is dark red or reddish, a darker part is observed near the center of the shadow.
3 points - a brick-red eclipse, the shadow is surrounded by a grayish or yellowish border.
4 points - a copper-red eclipse, very bright, the outer zone is light, bluish.
If the plane of the Moon's orbit coincided with the plane of the ecliptic, then lunar eclipses would be repeated every month. But the angle between these planes is 5° and the Moon only crosses the ecliptic twice a month at two points called the nodes of the lunar orbit. Ancient astronomers knew about these nodes, calling them the Head and Tail of the Dragon (Rahu and Ketu). In order for a lunar eclipse to occur, the Moon must be near the node of its orbit during a full moon. There are usually 1-2 lunar eclipses per year. Some years there may be none at all, and sometimes a third thing happens. In the rarest cases, a fourth eclipse occurs, but only a partial penumbral one.
10. History of lunar exploration
Exploration of the Moon using spacecraft began on September 14, 1959, with the collision of the Luna-2 automatic station with the surface of our satellite. Until this point, the only method of exploring the Moon was by observing the Moon. Galileo's invention of the telescope in 1609 was a major milestone in astronomy, particularly in the observation of the Moon. Galileo himself used his telescope to study the mountains and craters on the lunar surface.
Since the start of the space race between the USSR and the US during the Cold War, the Moon has been at the center of both the USSR and US space programs. From the US perspective, the 1969 moon landing was the culmination of the lunar race. On the other hand, many significant scientific milestones were achieved by the Soviet Union before the United States. For example, the first photographs of the far side of the Moon were taken by a Soviet satellite in 1959.
The first man-made object to reach the Moon was the Soviet station Luna 2. The far side of the Moon was photographed by the Luna 3 station on October 7, 1959. After these and other achievements of the USSR in space exploration, US President John Kennedy formulated the main US task in space as landing on the Moon.
Despite all the efforts of the United States, the Soviet Union remained a leader in lunar exploration for a long time. The Luna 9 station was the first to make a soft landing on the surface of our natural satellite. After landing, Luna 9 transmitted the first photographs of the lunar surface. The landing of Luna 9 proved the possibility of a safe landing on the Moon. This was especially important because until that moment it was believed that the surface of the Moon consisted of a layer of dust, which could be several meters thick and any object would simply “drown” in this layer of dust. The first artificial satellite of the Moon was also the Soviet station Luna-10, launched on March 31, 1966.
The American program for manned exploration of the Moon was called Apollo. It brought its first practical result on December 24, 1968, with the Apollo 8 spacecraft flying around the Moon. Humanity first set foot on the surface of the Moon on July 20, 1969. The first person to leave his mark on the Moon was Neil Armstrong, commander of Apollo 11. The first automatic robot on the surface of the Moon was the Soviet Lunokhod-1, which landed on the Moon on November 17, 1970. The last man walked on the moon in 1972.
Samples of lunar rock were delivered to Earth as part of the Soviet Luna program by automatic stations Luna-16, 20 and 24. Also, samples of lunar rock were delivered to Earth by astronauts of the Apollo mission.
From the mid-1960s to the mid-1970s, 65 man-made objects reached the lunar surface. But after the Luna-26 station, lunar exploration virtually ceased. The Soviet Union switched its exploration to Venus and the United States to Mars.
XXI century: On October 9, 2009, the LCROSS spacecraft and the Centaurus upper stage made a planned fall onto the lunar surface into the Cabeus crater, located approximately 100 km from the lunar south pole, and therefore constantly located in deep shadow. On November 13, NASA announced that water had been discovered on the Moon using this experiment.
It is possible that the Moon may contain not only silver, mercury and alcohols, but also other chemical elements and compounds. Water ice, molecular hydrogen found by the LCROSS and LRO missions in the lunar crater Cabeus indicate that the Moon does have resources that could be exploited by future missions.
Conclusion
The Moon could become an excellent platform for carrying out the most complex observations in all branches of astronomy. Therefore, astronomers are likely to be the first scientists to return to the Moon. The Moon could become a base station for space exploration beyond its orbit. Thanks to the small force of lunar gravity, launching a huge space station from the Moon would be 20 times cheaper and easier than Earth. Water and breathable gases could be produced on the Moon because lunar rocks contain hydrogen and oxygen. Rich reserves of aluminum, iron and silicon would provide a source of building materials.
A lunar base would be very important for further searches for valuable raw materials available on the Moon, for solving various engineering problems and for space research carried out under lunar conditions.
In many ways, the Moon would be an ideal location for an observatory. Observations beyond the atmosphere are now made using telescopes orbiting the Earth, such as the Hubble Space Telescope; but telescopes on the Moon would be far superior in every respect. Instruments on the far side of the Moon are protected from light reflected by the Earth, and the Moon's slow rotation on its axis means that lunar nights last for 14 of our days. This would allow astronomers to conduct continuous observations of any star or galaxy for much longer than is currently possible.
Pollution on Earth is making it increasingly difficult to observe the sky. Light from big cities, smoke and volcanic eruptions pollute the skies, and television stations interfere with radio astronomy. In addition, it is impossible to observe infrared, ultraviolet and x-ray radiation from the Earth. The next important step in studying the Universe could be the creation of a scientific settlement on the Moon.
Bibliography
1.Galkin I.N., Shvarev V.V. “Structure of the Moon” - M., “Znanie”, 1977.
2. Siegel F.Yu. "Lunar Horizons" - M., "Enlightenment", 1976.
3. Open astronomy - M., Physikon, 1999-2005.
4. http://full-moon.ru/
5. http://www.geokhi.ru/
6. http://www.krugosvet.ru/
7. http://ru.wikipedia.org/
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The Moon is the celestial body located closest to the Earth, which is its natural satellite and the brightest object after the Sun. In addition, it is also the only object in the solar system that humans have set foot on.
The moon has attracted attention at all times. People have looked at it for centuries, admiring the lunar craters, trying to study its origin and laws. The moon rotates in the same direction as most celestial bodies. It moves around the Earth at a speed of about 1 km/s. Since there is no atmosphere there, there is no water, no air, no weather on the Moon. And the temperature has a fairly wide range: from –120 °C to +110 °C. The force of gravity is 6 times less than Earth's (1.62 m/s2). As early as 1610, Galileo Galilei used telescopic equipment to observe the lunar surface and discover various depressions and craters.
Extended darkish spots, or “Moon Seas” as they are called, occupy about 40% of the visible lunar relief. In the old days, meteorite and asteroid attacks on the lunar surface were commonplace. It is even possible that the Moon took upon itself all the blows of celestial bodies that were intended for our Earth! But she, like a kind of shield, repelled all attacks. Perhaps it is the Moon that we should say thank you for the fact that life on our planet did not disappear from the fall of some meteorite or asteroid. Now, the frequency of collisions of celestial bodies with the Moon is practically zero, but the craters that we can observe on the surface of the Moon remain forever, as a kind of reminder of the merits of our faithful satellite.
Structure of the Moon
The mass of the Earth's satellite is 81 times less than our planet. To study the lunar structure, various methods were used, including seismic ones. The upper layer of the lunar surface is represented by the crust, the thickness of which reaches 60 km. The crust consists of the rock basalt. In marine and continental areas, its composition has significant differences. The mantle - located under the lunar crust, is divided into the upper - 250 km, the middle - 500 km and the lower - 1000 km. Up to this level, the substance of the subsoil is in a solid state, and is a cold and powerful lithosphere, with undamped seismic vibrations. Nearing the end of the lower mantle boundary, the temperature increases, approaching the melting point, so seismic waves are quickly absorbed. This part of the satellite is the lunar asthenosphere, in the center of which there is a liquid core consisting of iron sulfide with a radius of 350 km. The temperature in it ranges from 1300K to 1900K, with a mass of no more than 2% of the mass of the entire Moon.
It is known that the Moon is turned to the Earth, only on one side, so everyone has long dreamed of finding out what secrets the other side of the Moon hides. By itself, the Moon does not glow. It’s just that the sun’s rays, reflected from the Earth, illuminate its different parts. In this regard, the phases of the moon are also explained. It is turned to us with its dark side and moves in orbit between the Sun and Earth. Every month there is a new moon. The next day, a bright crescent of a “renewed” Moon appears in the western sky. The rest of the Moon receives virtually no light reflected from the Earth. In a week, half of the Moon's disk can be observed. After 22 days, the last quarter is observed. And on the 30th day the new moon comes again.
Characteristics of the Moon
Mass: 0.0123 Earth masses, that is 7.35 * 1022 kg
Diameter at the equator: 0.273 times the diameter of the Earth, i.e. 3476 km
Axis tilt: 1.55°
Density: 3346.4 kg/m3
Surface temperature: –54 °C
Distance from satellite to planet: 384400 km
Speed around the planet: 1.02 km/s
Orbital eccentricity: e = 0.055
Orbital inclination to the ecliptic: i = 5.1°
Gravity acceleration: g = 1.62 m/s2
Features of the "structure" - surface
How were lunar craters formed? This question became the reason for a long discussion, which, with the light hand of the Spanish astronomer Antonio Palusi-Borel, was called the “Hundred Years War”. 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. Stanyukovich's explosive theory was developed in 1947-1960. themselves, and then by other researchers.
Flights to the Moon starting in 1964 by American spacecraft of the Ranger series, the discovery of craters on Mars and Mercury, and then on planetary satellites and asteroids brought the final result in this “hundred-year war”, which lasted not 100 years, but much longer. The meteritic theory is now generally accepted.
In 1811, French astronomer Francois Arago discovered the polarization of light reflected by the Moon. This meant that the lunar surface would have to be covered with a layer of finely crushed soil. In the seas the polarization was stronger than on the continents.
In 1918, Russian scientist Nikolai Pavlovich Barabashov, while studying the dependence of the brightness of lunar formations on the angle of incidence of solar rays, discovered a strange circumstance. Each section of the lunar surface reaches its maximum brightness not when the Sun is at its zenith above it, as one would expect, but during the full moon, when the reflected ray meets the incident solar ray.
It took some time for astronomers to figure out the reasons for this phenomenon. Clear ideas about the nature of the lunar surface were formed only in the middle of the 20th century. In the 50s it was found that the lunar soil is indeed finely crushed (obviously by impacts of small meteorites), and such a substance, as shown by theoretical studies and special experiments, reflects the most light in the direction from which the illuminating beam comes.
In 1959, Russian researcher Nadezhda Nikolaevna Sytinskaya proposed the meteoric-slag theory of the formation of lunar soil. According to this theory, the heat transferred during a meteorite impact to the outer cover - the regolith of the Moon - is spent not only on its melting and evaporation, but also on the formation of slags, which manifest themselves in the color features of the lunar surface.
The meteor-slag theory was for some time opposed by the dust hypothesis of the American astronomer Thomas Gold. He believed that the Moon was covered with a thick layer of dust, in which spacecraft and the astronauts themselves could drown when descending to its surface. The soft landing on the Moon of the Soviet automatic interplanetary station Luna-9 on February 3, 1966 completely refuted this point of view. American astronauts Neil Armstrong and Edwin Aldrin, who first set foot on the lunar surface on July 21, 1969, were able to verify the validity of the meteor-slag theory.
Back in the 19th century. The temperature of the lunar surface was measured, its changes were monitored during the lunar day, as well as during eclipses, when the Moon plunges into the shadow of the Earth and is thus deprived of sunlight and heat. Due to the absence of an atmosphere during the daytime (which is 14.7 Earth days), under the influence of the burning rays of the sun it heats up to 120-130°C. At night, the lunar heat freely escapes into outer space and the temperature drops to -150°C. Something similar is observed during lunar eclipses.
Internal structure of the Moon
The density of the Moon is 3340 kg/m 3 - the same as that of the Earth's mantle. This means that our satellite either does not have a dense iron core, or it is very small. More detailed studies were obtained as a result of seismic experiments.
Seismic exploration of the Moon began as a curiosity. At the very end of the first manned expedition to the Moon, astronauts Neil Armstrong and Edwin Aldrin, moving 20 m south of the lunar ship, installed a seismometer - one of two scientific instruments that they left on the Moon (the second was a quartz reflector for laser ranging from Earth) . The astronauts had to install this device very carefully, oriented to the cardinal points and vertically, since then no one would be able to approach it to fix a possible problem. Observations with this seismometer were supposed to show whether there is modern tectonic activity on the Moon, or whether it is a geologically dead celestial body. As soon as the seismometer was installed, it was immediately turned on by command from the Mission Control Center on Earth. Those present in the hall of the Control Center on the outskirts of the Texas city of Houston were surprised to see that the device immediately began to report moonquakes. They occurred continuously, in the form of a whole series of successive shocks. However, it soon became clear that this was not the result of unrest in the lunar interior - the surface of our satellite was shaken by the steps of two astronauts moving away from the seismometer to their spacecraft. The device was so sensitive that it could detect a pea-sized rock falling onto the lunar surface at a distance of 1 km from the seismometer location.
This seismometer subsequently reported numerous tremors inside the Moon, dispelling the idea that geological activity on the moon had long ceased. It turned out that seismic tremors occur regularly on the Moon, but they are very different from earthquakes on our planet. Subsequently, four more seismometers were left on the lunar surface. Long-term observations with their help made it possible to register thousands of moonquakes, most of which were repeated many times in the same sources. Between 600 and 3,000 seismic events occur on the Moon per year. Four types of moonquakes have been identified - tidal, tectonic,
meteorite And thermal. Tidal movements of the Moon occur twice a month, every two weeks, when the Moon is in line with the Earth and the Sun, that is, during full moons and new moons. During these periods, the effect of the tidal forces of the Earth and the Sun on the Moon intensifies. When these three celestial bodies are located on the same line, the forces of their mutual influence on each other are summed up, which leads to the occurrence of moonquakes on the Moon at a depth of 800-1000 km.
Tectonic moonquakes occur during movements in the shallow layers of the Moon (100-300 km). They occur less frequently than tidal waves, and their strength is much weaker.
The source of meteorite moonquakes are explosions that occur when meteorites fall onto the surface of the Moon. Most moonquakes of this type occur when the Moon's orbit is crossed by a meteor shower. But there may also be falls of single meteorites.
Thermal moonquakes, the weakest of all, begin at sunrise, when, after a long night, lasting about 14 Earth days on the Moon, the cold surface begins to heat up sharply. In this case, ground movements occur on steep slopes, landslides, screes and other displacements of the upper layer, leading to slight tremors of the lunar surface.
Observations carried out from 1969 to 1978 showed that the Moon is very “sounding” - it continues to vibrate after moonquakes for an hour, and sometimes longer. Such tremors differ sharply from those on Earth, where surface vibrations last only a few minutes. The lack of water on the Moon is the main reason for the duration of the oscillations. The presence of water in rocks serves as a strong shock absorber on the earth, dampening vibration.
The oscillations of the Moon during seismic events - weak and long-lasting - resemble a quiet, drawn-out howl, in contrast to the strong but short-lived oscillations of the Earth, which resemble a loud, sharp scream.
Asymmetrical Moon
As a result of the research, it turned out that our natural satellite turned out to be geologically asymmetrical - almost all moonquakes recorded by seismometers over 8 years of observations occurred on the visible side of the Moon. On the far side, only five epicenters of moonquakes are known, while on the visible side there are several dozen. A similar asymmetry is observed in the distribution of the main types of relief on the surface of the Moon - seas and continents. Almost all dark areas - lunar seas - are located only on the visible side. These are plains composed of dark material - basaltic lavas, similar to those found on the Central Siberian Plateau. The light areas, called the lunar continent, occupy 2/3 of the visible side of the Moon, and the seas are interspersed into it in separate small areas. The lunar continent is more ancient than the seas; it was formed 4.5 billion years ago, and 3 billion years ago its lowest parts were flooded by basalts that poured out from the bowels of the Moon. The Moon's volcanic and seismic activity peaked 3 billion years ago, when extensive lava eruptions occurred, creating the dark basalt plains of the lunar seas.
The energy released per year during moonquakes is several billion times less than that of earthquakes. Most of this energy is released at depths of 600-800 km, that is, at the bottom of the solid shell of the Moon - the lithosphere. Deeper than this layer, the substance is in a partially molten state (asthenosphere), and in the very center of the Moon there may be a completely molten small core of iron sulfide.
The main reasons for the seismic activity of the Moon are the tidal influence of the Earth and the fall of large meteorites. Meteor moonquakes can cause the slopes of lunar craters to collapse until they become flat enough to prevent landslides from forming on them.
On the Moon, the energy loss of elastic waves is very small, so earthquakes are felt at very large distances from the epicenter of the seismic event. Moreover, on the Moon the amplitude of oscillations is much smaller than on Earth. A person standing on the surface of the Moon will not even feel that the ground beneath him is shaking. But the secondary effects of lunar seismic activity can serve as a source of danger for people or instruments on the Moon. Weak attenuation of seismic waves can lead to collapses of crater slopes or landslides in mountainous areas over large areas and at great distances from the epicenter. The astronauts of Apollo 17, the last expedition to the Moon, which took place in 1972, investigated a landslide, the formation of which is associated with a meteorite impact that created the Tycho crater 100 million years ago, located 2,000 km from the expedition site. However, the likelihood of major seismic events is very low. Such moonquakes only occur when large meteorites fall, which is extremely rare.
Lantern for the rocky depths
Seismology is the study of earthquakes and the causes that give rise to them, a science whose name comes from the Greek word “seismos”, which means “oscillations”. One of the founders of seismology, Russian physicist Academician Golitsyn, figuratively noted back in 1912 that “every earthquake can be likened to a lantern that lights up for a short time and illuminates the insides of the Earth, thereby allowing us to see what is happening there.” Indeed, almost all modern ideas about the internal structure of our planet are based on the interpretation
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Missile strikes on the Moon
The astronauts themselves, in order to cause “translucency” of the lunar interior, deliberately created moonquakes in various ways. For example, the Apollo 12 astronauts, after returning to the orbital ship, dropped their lunar compartment from orbit onto the surface of the Moon. Apollo 14 astronauts Shepard and Mitchell conducted a seismic experiment in which they detonated 13 small charges located on the lunar surface. Explosions of such charges, installed at the end of a pole with which the astronaut rested on the lunar soil, created small moonquakes. Seismic waves from them were recorded by a device installed nearby. In this way, information was obtained about the structure of the lunar interior at a depth of several tens of meters. Leaving the Moon, several expeditions left grenade launchers on its surface, which were subsequently activated by commands from the Earth. The explosions of these grenades provided insight into the structure of the upper layers of the lunar crust at a greater depth than the explosions carried out by the astronauts themselves using hand-held devices.
The fall of four lunar modules of the Apollo spacecraft and the last five stages of the Saturn V lunar launch vehicle to the Moon showed that a powerful continental crust covers the entire Moon, without dividing, as on Earth, into separate continents, and only in some places it thins out and is covered by basalt covers. Beneath the crust to a depth of 800 km lies the mantle, in which, starting at a depth of about 100 km, signs of weak modern activity appear, manifested by moonquakes. Below 800 km, apparently, a significant amount of melt appears, which does not transmit transverse seismic waves. The epicenters of moonquakes form two wide, blurred belts that do not coincide with the belts of the dark seas.
Theories of the origin of the Moon
Over the past 120 years, three hypotheses have been put forward for the origin of our satellite. The first 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 (such ideas about the Earth’s past prevailed at the end of the 19th century). 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, mathematician 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. According to Australian geophysicist Edward Ringwood, who has worked extensively on the problem of the origin of the Moon, of all the hypotheses created before the launch of the Apollo series spacecraft, only the Ruskol model does not have serious shortcomings. Its development continues...
Photo: Moon- a natural satellite of the Earth and a unique alien world visited by humanity.
Moon
Characteristics of the Moon
The Moon revolves around the Earth in an orbit whose semi-major axis is 383,000 km (ellipticity 0.055). The plane of the lunar orbit is inclined to the plane of the ecliptic at an angle of 5°09. Rotation period equals 27 days 7 hours 43 minutes. This is the sidereal or sidereal period. The synodic period - the period of change of lunar phases - is equal to 29 days 12 hours 44 minutes. The period of rotation of the Moon around its axis is equal to the sidereal period. Because the time of one revolution The Moon around the Earth is exactly equal to the time of one revolution around its axis, the Moon always facing the Earth the same side. The Moon is the most visible object in the sky after Sun. Maximum magnitude equal to – 12.7m.
Weight Earth's satellite is 7.3476*1022 kg (81.3 times less than the mass of the Earth), average density p = 3.35 g/cm3, equatorial radius - 1,737 km. There is almost no contraction from the poles. The acceleration of gravity on the surface is g = 1.63 m/s2. The Moon's gravity could not retain its atmosphere, if it ever had one.
Internal structure
Density The density of the Moon is comparable to the density of the Earth's mantle. Therefore, the Moon either has no or very insignificant iron core. The internal structure of the Moon was studied using seismic data transmitted to Earth by devices of the Apollo space expeditions. The thickness of the Moon's crust is 60–100 km.
Photo: Moon - internal structure
Thickness upper mantle 400 km. In it, seismic velocities depend on depth and decrease depending on distance. Thickness middle mantle about 600 km. In the middle mantle, seismic velocities are constant. Lower mantle located below 1100 km. Core The Moon, starting at a depth of 1500 km, is probably liquid. It contains virtually no iron. As a result, the Moon has a very weak magnetic field, not exceeding one ten-thousandth of the Earth's magnetic field. Local magnetic anomalies have been recorded.
Atmosphere
There is virtually no atmosphere on the Moon. This explains the sudden temperature changes several hundred degrees. During the daytime, the surface temperature reaches 130 C, and at night it drops to –170 C. At the same time, at a depth of 1 m, the temperature is almost always constant. Sky above the Moon is always black, since for the formation of a blue color of the sky it is necessary air, which is missing there. There is no weather there, and the winds do not blow. In addition, the moon reigns complete silence.
Photo: the surface of the Moon and its atmosphere
Visible part
Only visible from Earth visible part of the Moon. But this is not 50% of the surface, but a little more. The Moon revolves around the Earth ellipse, near perigee the Moon moves faster, and near apogee it moves slower. But the Moon rotates uniformly around its axis. As a result, an oscillation in longitude is formed. Its probable maximum value is 7°54. Due to libration, we have a chance to observe from the Earth, in addition to the visible side of the Moon, also the adjacent narrow strips of the territory of its reverse side. In total, 59% of the lunar surface can be seen from Earth.
Moon in early times
There is an assumption that in the early times of its history, the Moon rotated around its axis faster and, therefore, turned towards the Earth with various parts of its surface. But due to the proximity of the massive Earth, impressive tidal waves were generated in the solid body of the Moon. The process of deceleration of the Moon lasted until it was invariably turned to us with only one side.
