School encyclopedia. Origin of the Moon: versions Historical views on the origin of the moon

A few words from the history of the problem

Of the planets in the inner solar system, which includes Mercury, Venus, Earth and Mars, only Earth has a massive satellite, the Moon. Mars also has satellites: Phobos and Deimos, but these are small bodies of irregular shape. The largest of them, Phobos, is only 20 km in maximum dimension, while the diameter of the Moon is 3560 km.

The Moon and Earth have different densities. This is caused not only by the fact that the Earth is large and, therefore, its interior is under greater pressure. The average density of the Earth, normalized to normal pressure (1 atm) is 4.45 g/cm 3 , the density of the Moon is 3.3 g/cm 3 . The difference is due to the fact that the Earth contains a massive iron-nickel core (with an admixture of light elements), which contains 32% of the Earth's mass. The size of the Moon's core remains unclear. But taking into account the low density of the Moon and the limitation imposed by the value of the moment of inertia (0.3931), the Moon cannot contain a core exceeding 5% of its mass. The most probable, based on the interpretation of geophysical data, is considered to be an interval of 1–3%, that is, the radius of the lunar core is 250–450 km.

By the middle of the last century, several hypotheses of the origin of the Moon had been formed: the separation of the Moon from the Earth; accidental capture of the Moon into low-Earth orbit; coaccretion of the Moon and Earth from a swarm solids. Until recently, this problem was solved by specialists in the field of celestial mechanics, astronomy and planetary physics. Geologists and geochemists did not take part in it, since nothing was known about the composition of the Moon before the start of its study by spacecraft.

Already in the 30s. last century, it was shown that the hypothesis of the separation of the Moon from the Earth, put forward, by the way, by J. Darwin, the son of Charles Darwin, is untenable. The total rotational moment of the Earth and the Moon is insufficient for the occurrence of rotational instability (loss of matter under the influence of centrifugal force) even in the liquid Earth.

In the 60s Experts in the field of celestial mechanics came to the conclusion that the capture of the Moon into low-Earth orbit is an extremely unlikely event. There remained the coaccretion hypothesis, which was developed by domestic researchers, students of O.Yu. Shmidt V.S. Safronov and E.L. Ruskol. Her weak side– inability to explain the different densities of the Moon and Earth. Clever but implausible scenarios were invented for how the Moon could lose excess iron. When details of the chemical structure and composition of the Moon became known, this hypothesis was finally rejected. Just in the mid-1970s. a new scenario for the formation of the Moon has emerged. American scientists A. Cameron and V. Ward and at the same time V. Hartman and D. Davis in 1975 proposed a hypothesis of the formation of the Moon as a result of a catastrophic collision with the Earth of a large cosmic body the size of Mars (mega-impact hypothesis). As a result, a huge mass of earthly matter and partly the material of the impactor (a celestial body that collided with the Earth) melted and was thrown into low-Earth orbit. This material quickly accumulated into a compact body that became the Moon. Despite its apparent exoticism, this hypothesis became generally accepted because it offered a simple solution to a number of problems. As computer modeling has shown, from a dynamic point of view, the collision scenario is quite feasible. Moreover, he provides an explanation for the increased angular momentum of the Earth-Moon system and the tilt of the Earth's axis. The lower iron content in the Moon is also easily explained, since it is assumed that a catastrophic collision occurred after the formation of the Earth's core. Iron turned out to be mainly concentrated in the Earth's core, and the Moon was formed from the rocky material of the Earth's mantle.

Rice. 1 – The collision of the Earth with a celestial body approximately the size of Mars, which resulted in the ejection of molten matter that formed the Moon (mega-impact hypothesis).
Drawing by V.E. Kulikovsky.

By the mid-1970s, when samples of lunar soil were delivered to Earth, the geochemical properties of the Moon were quite well studied, and in a number of parameters it actually showed good similarity with the composition of the Earth’s mantle. Therefore, such prominent geochemists as A. Ringwood (Australia) and H. Wenke (Germany) supported the mega-impact hypothesis. In general, the problem of the origin of the Moon from the category of astronomical ones rather moved into the category of geological and geochemical ones, since it was geochemical arguments that became decisive in the system of evidence for one or another version of the formation of the Moon. These versions differed only in details: the relative sizes of the Earth and the impactor, what was the age of the Earth when the collision occurred. The strike concept itself was considered unshakable. Meanwhile, some details of the geochemical analysis cast doubt on the hypothesis as a whole.

The problem of "volatile" and isotope fractionation

The issue of iron deficiency on the Moon played a decisive role in the discussion of the origin of the Moon. Another fundamental problem - the extreme depletion of the Earth's natural satellite in volatile elements - remained in the shadows.

The Moon contains many times less K, Na and other volatile elements compared to carbonaceous chondrites. The composition of carbonaceous chondrites is considered to be closest to the original cosmic matter from which the bodies of the Solar System were formed. We usually perceive as “volatile” compounds of carbon, nitrogen, sulfur and water, which easily evaporate when heated to a temperature of 100–200 o C. At temperatures of 300–500 o C, especially under low pressure conditions, for example, in contact with vacuum of space, volatility is characteristic of elements that we usually observe in the composition of solids. The Earth also contains few volatile elements, but the Moon is noticeably depleted in them even compared to the Earth.

It would seem that there is nothing surprising in this. Indeed, in accordance with the impact hypothesis, it is assumed that the Moon was formed as a result of the ejection of molten matter into near-Earth orbit. It is clear that in this case part of the substance could evaporate. Everything would be well explained if not for one detail. The fact is that during evaporation a phenomenon called isotope fractionation occurs. For example, carbon consists of two isotopes 12 C and 13 C, oxygen has three isotopes - 16 O, 17 O and 18 O, the element Mg contains stable isotopes 24 Mg and 26 Mg, etc. During evaporation, the light isotope outstrips the heavy one, so the residual substance must be enriched in the heavy isotope of the element that was lost. The American scientist R. Clayton and his colleagues showed experimentally that with the observed loss of potassium on the Moon, the ratio 41 K/39 K should have changed by 60‰. With the evaporation of 40% of the melt, the isotope ratio of magnesium (26 Mg/ 24 Mg) would change by 11–13‰, and silicon (30 Si/ 28 Si) – by 8–10‰. These are very large shifts, considering that the modern accuracy of measuring the isotopic composition of these elements is no worse than 0.5‰. Meanwhile, no shift in the isotopic composition, that is, any traces of isotopic fractionation of volatiles, was found in the lunar substance.

A dramatic situation arose. On the one hand, the impact hypothesis was proclaimed unshakable, especially in the American scientific literature, on the other hand, it was not combined with isotopic data.

R. Clayton (1995) noted: "These isotopic data are inconsistent with almost all proposed mechanisms for depletion of volatile elements by evaporation of condensed matter." H. Jones and H. Palme (2000) concluded that "evaporation cannot be considered as a mechanism leading to volatile depletion due to irreducible isotopic fractionation."

Moon formation model

Ten years ago, I put forward a hypothesis, the meaning of which was that the Moon was formed not as a result of a catastrophic impact, but as a binary system simultaneously with the Earth as a result of the fragmentation of a cloud of dust particles. This is how double stars are formed. Iron, which the Moon is depleted of, was lost along with other volatiles as a result of evaporation.

Rice. 2 – Formation of the Earth and the Moon from a common dust disk in accordance with the author’s hypothesis about the origin of the Earth and the Moon as a binary system.

But can such fragmentation actually occur at the values ​​of mass, angular momentum, and other things that the Earth-Moon system has? This remained unknown. Several researchers joined a group to study this problem. It included well-known experts in the field of space ballistics: academician T.M. Eneev, back in the 70s. who investigated the possibility of accumulation of planetary bodies by combining dust concentrations; famous mathematician academician V.P. Myasnikov (unfortunately, has already passed away); a major specialist in the field of gas dynamics and supercomputers, Corresponding Member of the Russian Academy of Sciences A.V. Zabrodin; Doctor of Physical and Mathematical Sciences M.S. Easy access; Doctor of Chemical Sciences Yu.I. Sidorov. Later we were joined by Doctor of Physical and Mathematical Sciences, specialist in the field of computer modeling A.M. Krivtsov from St. Petersburg, who made a significant contribution to solving the problem. Our efforts were aimed at solving the dynamic problem of the formation of the Moon and Earth.

However, the idea of ​​the Moon losing iron through evaporation would seem to be in as much conflict with the lack of traces of isotopic fractionation on the Moon as the impact hypothesis. In fact, there was a remarkable difference here. The fact is that isotope fractionation occurs when isotopes irreversibly leave the surface of the melt. Then, due to the greater mobility of the light isotope, a kinetic isotope effect occurs (the above values ​​of isotope shifts are due precisely to this effect). But another situation is possible when evaporation occurs in a closed system. In this case, the evaporated molecule can return to the melt again. Then some equilibrium is established between the melt and steam. It is clear that more volatile components accumulate in the vapor phase. But due to the fact that there is both direct and reverse transition of molecules between steam and melt, the isotope effect turns out to be very small. This is a thermodynamic isotope effect. At elevated temperatures it can be negligible. Idea closed system is not applicable to the melt ejected into low-Earth orbit and evaporating into outer space. But it fully corresponds to the process occurring in a cloud of particles. The evaporating particles are surrounded by their vapor, and the cloud as a whole is in a closed system.

Rice. 3 – Kinetic and thermodynamic isotope effects: a) the kinetic isotope effect during melt evaporation leads to the enrichment of the steam with light isotopes of volatile elements, and the melt with heavy isotopes; b) thermodynamic isotope effect that occurs when there is equilibrium between liquid and vapor. It may be negligible at elevated temperatures; c) a closed system of particles surrounded by their own vapor. Evaporated particles can return to the melt again.

Let us now assume that the cloud is compressed as a result of gravity. It collapses. Then the part of the substance that has turned into vapor is squeezed out of the cloud, and the remaining particles turn out to be depleted of volatiles. In this case, almost no fractionation of isotopes is observed!

Several versions of the solution to the dynamic problem were considered. The most successful model of particle dynamics (a variant of the molecular dynamics model) proposed by A.M. Krivtsov.

Let's imagine that there is a cloud of particles, each of which moves in accordance with the equation of Newton's second law, as is known, including mass, acceleration and the force causing the movement. The force of interaction between each particle and all other particles f includes several components: gravitational interaction, elastic force acting upon collision of particles (manifests itself at very small distances), and the inelastic part of the interaction, as a result of which the collision energy is converted into heat.

It was necessary to accept certain initial conditions. The solution was carried out for a cloud of particles that has the mass of the Earth–Moon system and has angular momentum characterizing the system of these bodies. In fact, these parameters for the initial cloud could differ slightly, both up and down. Based on the convenience of computer calculations, a two-dimensional model was considered - a disk with an unevenly distributed surface density. In order to describe the behavior of a real three-dimensional object in the parameters of a two-dimensional model, similarity criteria were introduced using dimensionless coefficients. Another condition: it was necessary to attribute to the particle, in addition to the angular velocity, a certain chaotic velocity. Mathematical calculations and some other technical details can be omitted here.

A computer calculation of a model based on the above principles and conditions well describes the collapse of a cloud of particles. In this case, a central body of elevated temperature was formed. However, the main thing was missing. There was no fragmentation of the particle cloud, that is, one body arose, and not the Earth-Moon binary system. Generally speaking, there was nothing unexpected in this. As already mentioned, attempts to simulate the formation of the Moon by breaking away from the rapidly rotating Earth have previously been unsuccessful. The angular momentum of the Earth-Moon system was insufficient to split the overall body into two fragments. The same thing happened with the cloud of particles.

However, the situation changed radically when the phenomenon of evaporation was taken into account.

The process of evaporation from the particle surface causes a repulsion effect. The force of this repulsion is inversely proportional to the square of the distance from the evaporating particle:

where λ is a proportionality coefficient that takes into account the magnitude of the flow evaporating from the surface of the particle; m is the mass of the particle.

The structure of the formula characterizing gas-dynamic repulsion looks similar to the expression for the gravitational force, if instead of λ we substitute γ - the gravitational constant. Strictly speaking, there is no complete similarity of these forces, since the gravitational interaction is long-range, and the repulsive force of evaporation is local. However, as a first approximation, they can be combined:

This yields a certain effective constant γ", less than γ.

It is clear that a decrease in the coefficient γ will lead to the appearance of rotational instability at lower values ​​of angular momentum. The question is what should be the evaporation flux so that the requirements for the initial angular velocity of the cloud decrease so much that the real angular momentum of the Earth-Moon system turns out to be sufficient for fragmentation to occur.

The estimates performed showed that the flow should be very small and fit into quite plausible values ​​of time and mass. Namely, for chondrules (spherical particles that make up chondrite meteorites) with a size of approximately 1 mm, with a temperature of the order of 1000 K and a density of ~ 2 g/cm 3 , the flux should be approximately 10–13 kg/m 2 s. In this case, a decrease in the mass of the evaporating particle by 40% will take a time of the order of (3 - 7) 10 4 years, which is consistent with the possible order of 10 5 years for the time scale of the initial accumulation of planetary bodies. Computer simulations using real parameters clearly showed the emergence of rotational instability, culminating in the formation of two heated bodies, one of which would become the Earth, and the other the Moon.

Rice. 4 – Computer model of the collapse of a cloud of evaporating particles. The successive phases of cloud fragmentation (a–d) and the formation of a binary system (e–f) are shown. The calculations used real parameters characterizing the Earth–Moon system: kinetic moment K = 3.45 10 34 kg m 2 s –1 ; total mass of the Earth and Moon M = 6.05 10 24 kg, radius of the solid body c total mass Earth and Moon Rc = 6.41 10 6 m; gravitational constant "gamma" = 6.67 10 –11 kg –1 m 3 s –2; initial cloud radius R0 = 5.51 Rc; the number of calculated particles is N = 10 4, the value of the evaporation flux is 10 –13 kg m –2 s –1, corresponding to approximately 40% of the evaporation of the mass of particles with a chondrule size of about 1 mm over 10 4 – 10 5 years. An increase in temperature is conventionally shown by a change in color from blue to red.

Thus, the proposed dynamic model explains the possibility of the emergence of the Earth-Moon binary system. In this case, evaporation leads to the loss of volatile elements under conditions of a practically closed system, which ensures the absence of a noticeable isotope effect.

Iron deficiency problem

The explanation of the iron deficiency on the Moon compared to the Earth (and the primary cosmic matter - carbonaceous chondrites) at one time became the most convincing argument in favor of the impact hypothesis. It is true that the impact hypothesis has difficulties here too. Indeed, the Moon contains less iron than the Earth, but more than the Earth's mantle from which it is thought to have formed. Perhaps the Moon additionally inherited the impactor iron. But then it should be enriched not only with iron relative to the earth’s mantle, but also with siderophile elements (W, P, Mo, Co, Cd, Ni, Pt, Re, Os, etc.) accompanying iron. In iron-silicate melts they join the iron phase. Meanwhile, the Moon is depleted in siderophile elements, although it contains more iron than the Earth's mantle. IN latest models, in order to reconcile the impact hypothesis with observations, the mass of the impactor colliding with the Earth is increasingly increased, and a conclusion is drawn about its predominant contribution to the composition of the Moon's matter. But here a new complication arises for the impact hypothesis. The substance of the Moon, as follows from isotopic data, is strictly related to the substance of the Earth. Indeed, the isotopic compositions of samples from the Moon and Earth lie on the same line in the coordinates δ 18 O and δ 17 O (the ratio of the oxygen isotopes 17 O and 18 O to 16 O). This is how samples belonging to the same cosmic body behave. Samples of other cosmic bodies occupy other lines. As long as the Moon was considered to have formed from mantle material, the coincidence of isotopic characteristics supported this hypothesis. However, if the substance of the Moon is substantially formed from the substance of an unknown celestial body, the coincidence of isotopic characteristics no longer supports the impact hypothesis.

Rice. 5 – Comparative content of iron (Fe) and iron oxide (FeO) in the Earth and the Moon.

Rice. 6 – Diagram of oxygen isotope ratios δ 17 O and δ 18 O (δ 17 O and δ 18 O are values ​​characterizing the shifts in oxygen isotope ratios 17 O/ 16 O and 18 O/ 16 O, relative to the accepted SMOW standard). In this diagram, samples from the Moon and Earth fall along a common fractionation line, indicating the genetic relatedness of their composition.

The extreme depletion of the Moon in volatile elements and the role of evaporation in the dynamics of the formation of the Earth-Moon system allow us to interpret the problems of iron deficiency in a completely different way.

Based on our model, it is necessary to find out how the Moon is depleted in iron, and why the Moon is depleted in iron, but the Earth is not, despite the fact that as a result of fragmentation, two bodies with similar formation conditions arise.

Laboratory experiments have shown that iron is also a relatively volatile element. If you evaporate a melt that has a primary chondritic composition, then after the evaporation of the most volatile components (compounds of carbon, sulfur and a number of others), alkaline elements (K, Na) will begin to evaporate, and then it will be iron’s turn. Further evaporation will lead to volatilization of Si, followed by Mg. Ultimately, the melt will be enriched in the most difficult to volatile elements Al, Ca, Ti. The listed substances are among the rock-forming elements. They are part of the minerals that make up the bulk (99%) of rocks. Other elements form impurities and minor minerals.

Rice. 7 – After the formation of two hot nuclei (red spots), a significant part of the cooler (green and blue) material of the initial cloud of particles remains in the surrounding space (particle sizes are increased).

Note: The Earth's core (its mass is taken into account, which is 32% of the planet's mass) contains, in addition to iron, nickel and other siderophile elements, as well as up to 10% of light elements. It can be oxygen, sulfur, silicon, and, less likely, impurities of other elements. Data for the Moon are taken from S. Taylor (1979). Estimates of the composition of the Moon vary greatly among different authors. It seems to us that S. Taylor’s assessments are the most justified (Galimov, 2004).

The Moon is depleted in Fe and enriched in difficultly volatile elements: Al, Ca, Ti. The higher content of Si and Mg in the Moon is an illusion caused by iron deficiency. If the loss of volatiles is due to the evaporation process, then the content of only the most difficult to volatile elements will remain unchanged in relation to the original composition. Therefore, in order to make comparisons between chondrites (CI), the Earth and the Moon, all concentrations should be attributed to an element whose abundance is assumed to be constant.

Then the depletion of the Moon not only in iron, but also in silicon and magnesium is clearly revealed. Based on experimental data, this should be expected given a significant loss of iron during evaporation.

A. Hashimoto (1983) evaporated a melt that initially had a chondritic composition. An analysis of his experiment reveals that at 40% evaporation, the residual melt acquires a composition almost similar to that of the Moon. Thus, the composition of the Moon, including the observed iron deficiency, can be obtained during the formation of the Earth's satellite from primordial chondritic material. And then there is no need for the catastrophic impact hypothesis.

Asymmetry of growth of embryos of the Earth and the Moon

The second of the questions asked above remains - why the Earth is not depleted in iron, as well as silicon and magnesium, to the same extent as the Moon. The answer required solving another computer problem. First of all, we note that after fragmentation and the formation of two hot bodies in a collapsing cloud, a large amount of matter remains in the cloud of particles surrounding them. The surrounding mass of matter remains cold compared to the relatively high-temperature consolidated nuclei.

Rice. 8 – Computer simulations show that the larger of the resulting nuclei (red) develops much faster and accumulates most of the remaining initial cloud of particles (blue).

Initially, both fragments, both the one that was to become the Moon and the one that was to become the Earth, were depleted in volatiles and iron to almost the same extent. However, computer modeling showed that if one of the fragments turned out to be (by chance) slightly larger in mass than the other, then further accumulation of matter proceeds extremely asymmetrically. Germ bigger size grows much faster. As the difference in size increases, the difference in the rates of accumulation of matter from the remaining part of the cloud increases like an avalanche. As a result, the smaller embryo only slightly changes its composition, while the larger embryo (the future Earth) accumulates almost all of the primary matter of the cloud and ultimately acquires a composition very close to that of the primary chondritic matter, with the exception of the most volatile components, irrevocably leaving the collapsing cloud. Let us note again that the loss of volatile elements in this case occurs not due to evaporation in space, but due to the squeezing out of the residual vapor by the collapsing cloud.

Thus, the proposed model explains the super-depletion of the Moon in volatiles and the deficiency of iron in it. The main feature of the model is the introduction into consideration of the evaporation factor, and under conditions that exclude or reduce to small values ​​the fractionation of isotopes. This overcomes the fundamental difficulty faced by the mega-impact hypothesis. The evaporation factor made it possible for the first time to obtain a mathematical solution to the development of the Earth-Moon binary system under real physical parameters. It seems to us that the new concept we have proposed of the origin of the Moon from primordial matter, and not from the Earth’s mantle, is in better agreement with the facts than the American mega-impact hypothesis.

Upcoming Challenges

Although many questions have been answered, many still remain and a major new problem is emerging. It is as follows. In our calculations, we proceeded from the fact that the Earth and the Moon, at least their embryos measuring 2–3 thousand km, arose from a cloud of particles. Meanwhile, the existing theory of planetary accumulation describes the formation of planetary bodies as a result of the collision of solid bodies (planetesimals), first meter-long, then kilometer-long, hundred-kilometer, etc. sizes. Consequently, our model requires that during the early stage of development of a protoplanetary disk, large concentrations of dust, rather than an ensemble of solid bodies, arise in it and grow to an almost planetary mass. If this is really the case, then we're talking about not only about the model of the origin of the Earth-Moon system, but also about the need to revise the theory of planetary accumulation as a whole.

Questions remain regarding the following aspects of the hypothesis:

• a more detailed calculation of the temperature profile in a collapsing cloud is needed, combined with a thermodynamic analysis of the distribution of elements in the particle-vapor system at different levels of this profile (until this is done, the model remains rather a qualitative hypothesis);
• it is necessary to obtain a more rigorous expression for gas-dynamic repulsion, taking into account the local nature of the action of this force, in contrast to gravitational interaction.
• The model leaves aside the question of the influence of the Sun, the radius of the disk is chosen arbitrarily, and the deforming influence of the collision of clumps during the formation of the disk is not considered.
• to obtain a more rigorous solution, it would be important to move to a three-dimensional formulation of the problem and increase the number of model particles;
• it is necessary to consider cases of the formation of a binary system from a protodisk of less mass than the total mass of the Earth and the Moon, since it is likely that the accumulation process occurred in two stages - at the early stage - the collapse of the dust concentration with the formation of a binary system, and at the late stage - additional growth due to the collision of solid bodies formed by that time in the Solar System;
• in the dynamic part of our model the question of the cause remains undeveloped high value the initial moment of rotation of the Earth-Moon system and a noticeable inclination of the Earth’s axis to the ecliptic plane, while the mega-impact hypothesis offers such a solution.

The answers to these questions largely depend on the general solution to the above-mentioned problem of the evolution of condensations in the protoplanetary gas-dust disk around the Sun.

Finally, it should be borne in mind that our hypothesis assumes some elements of heterogeneous accretion (layer-by-layer formation of a celestial body), although in the opposite sense to that accepted. Proponents of heterogeneous accretion assumed that planets first form an iron core in one way or another, and then a predominantly silicate mantle shell grows. In our model, an iron-depleted embryo initially appears, and only subsequent accumulation brings forth iron-enriched material. It is clear that this significantly modifies the process of core formation and the associated conditions for fractionation of siderophile elements, and other geochemical parameters. Thus, the proposed concept opens up new aspects of research in the dynamics of the formation of the solar system and in geochemistry.

Earlier this week, astrophysicists from the Institute of Geophysics in Paris refuted the version of the origin Moon, which until now was considered the most probable. According to this hypothesis, approximately 4.5 billion years ago, the very young Earth collided with a protoplanet Teyei, resulting in the formation of the Moon.

Computer simulations carried out by experts have cast doubt on this version, and at the same time many of our other ideas about the origin of the cosmic body closest to Earth.

Editorial "MIR 24" chose the main versions of the origin of the satellite and, together with experts, weighed the pros and cons of popular hypotheses.

Version #1: one giant collision

The impact model for the formation of the Moon has remained dominant in science for the past three decades. Astrophysicists accepted it almost unanimously after the Apollo 17 lunar module delivered more than 110 kg of lunar rocks to Earth during its final landing on the satellite in December 1972.

Analysis of the chemical and isotopic composition of the soil led scientists to the idea that at the early stage of the formation of the Solar System, the Earth could have collided with a large celestial body - a protoplanet, the dimensions of which were commensurate with today's Mars, that is, approximately 10.7% of the Earth's mass.

“For both celestial bodies, this event was catastrophic, and the material that was ejected as a result of this collision partially remained in the Earth’s orbit for many millennia, which is why, as a result of evolutionary compression, the earth’s satellite was formed,” says Doctor of Physical and Mathematical Sciences , senior researcher at the Space Research Institute of the Russian Academy of Sciences Alexander Rodin.

The names of celestial bodies are traditionally given in Greek and mythological terms. Therefore, the hypothetical protoplanet was named in honor of one of the Titanide sisters, Theia, who, according to the beliefs of the ancient Greeks, was the mother of Selene (the Moon). The connection between the Earth and the satellite turned out to be so strong that over time the Moon began to cause ebbs and flows on the Blue Planet.

This, in turn, created the conditions on the wet firmament for the appearance of the first elements of biological life (nucleotides) from the simplest nitrogenous compounds, a mixture of phosphate and carbohydrates. So under the influence of lunar activity and sunlight on earth's surface the first “laboratory” for the formation of future life was formed.

The mega-explosion theory is supported by the fact that the core of the Earth’s satellite is too small for a planet that formed at the same time as the Earth (the radius of the Moon’s core is about 240 kilometers). In addition, the composition of the Moon is much more homogeneous than our planet. It seems that everything inclined scientists to the point of view that the reason for the birth of the Moon was the proto-beauty Theia.

Astronomers at the Paris Institute of Geophysics began to suspect the validity of such a beautiful hypothesis. The chemical compositions of the earth's mantle and lunar soil were confusing. Something was wrong there. As a result, Parisian astronomers launched a multi-year experiment, which has just ended.

During this experiment, they conducted 1.7 billion computer simulations of the collision between Earth and Theia and found that the mass of the hypothetical celestial body that Earth collided with could not be more than 15% of the mass of our planet.

Otherwise, the earth’s mantle would contain many times more nickel and cobalt, and the light isotopes of radioactive elements that are present in it now, for example, the helium-3 isotope, would have long since evaporated from the lunar soil.

Version No. 2: multiple bombing theory

“The latest French research confirms the assumption that there was not just one collision - there were many of them,” explains Dr. Rodin. “The future material for the formation of the satellite accumulated over millions of years in Earth’s orbit, and the bomber bodies themselves were much smaller than the hypothetical Theia.” .

However, according to the scientist, this discovery did not make an epoch-making revolution. In recent decades, the Moon has remained not only the most studied, but also the most actively studied object in the Solar System. Every year, scientists receive more and more new data that refute one or another of the existing hypotheses.

“Computer simulations only help us simulate certain conditions. Meteorologists work in much the same way, determining the weather for the near future. But we understand perfectly well that even a forecast for tomorrow may be incorrect. What can we say about such global events as the birth of living matter, the formation of the Moon or the Earth,” the scientist noted.

Doctor of Physics and Mathematics, Head of the Department of Lunar and Planetary Research at the Institute named after him, also agrees with him. P. K. Sternberg Moscow State University Vladimir Shevchenko.

According to him, French astrophysicists were several years ahead of the Russian scientist, director of the V.I. Vernadsky Institute of Geochemistry, Eric Galimov, who analyzed the hypothesis about the protoplanet Teiya and was one of the first in world science to refute it with arguments. True, purely theoretically. Now his theory has received experimental confirmation.

Version No. 3: “sister” hypothesis

The hypothesis that many Russian scientists are leaning toward today is this: the Moon and Earth formed relatively simultaneously from a single cloud of gas and dust. This happened about 4.5 billion years ago, which is confirmed by radioisotope dating data of meteorite samples, the so-called chondrites.

The “embryo” of the Earth attracted the maximum number of particles in the zone of their accessibility, and from the remaining fragments in orbit a smaller one, but similar in size, was formed chemical composition satellite.

“This theory removes dubious questions regarding the geochemical indicators of lunar soil,” explains Vladimir Shevchenko. “If a mega-impact had taken place, the Moon would have to contain the same substance that the Earth consisted of at that moment and would be much more similar to the Earth than it is now,” the professor sums up.

True, such a beautiful hypothesis about a common progenitor cloud does not explain much. For example, why the lunar orbit does not lie in the plane of the earth's equator and why its iron-nickel core was formed so miniature compared to ours.

Version No. 4: captive planet, or “marital” hypothesis

One of the most curious hypotheses, which has the least amount of evidence, is the hypothesis that the Moon originally formed as an independent planet of the solar system. As a result of the deviation of the celestial body from its orbit (the so-called perturbations), the planet, so to speak, “lost its course” and entered an elliptical orbit intersecting with the Earth.

During one of the approaches, the Moon fell into the field of the Earth's gravity and turned into its satellite.

American astronomers under the leadership of Thomas Jackson See were interested in this theory not for academic reasons. The fact is that the legends of the ancient African people Dogon they talked about the times when there was no second luminary in the night sky - the Moon.

Despite the fact that the theory did not fit into the “Big Three” academic hypotheses about the origin of the satellite, it was seriously discussed by a group of scientists led by Sergei Pavlovich Korolev when designing the automatic descent station.

Scientists had to “blindly” decide how the Moon was formed. The success of landing the station depended on their conclusions. After all, if the Moon revolves around the Earth for billions of years, without a dense atmosphere, a multi-meter layer of dust falling from space should have accumulated on its surface.

If this is really the case, the station intended for landing on the lunar firmament would simply drown.

Scientists clearly liked the assumption that the Moon was captured by the Earth relatively recently. In this case, its surface should still be hard. Therefore, they decided to rely on this scenario for the landing apparatus.

True, this theory has more contradictions than other versions of the origin of the satellite. For example, why are the oxygen isotopes on the Moon and Earth so identical?

Or why the Moon rotates in the same direction as the Earth, while the moons captured by Jupiter - Io, Europa, Ganymede and Callisto - rotate in a retrograde direction, that is, the opposite direction from Jupiter.

Be that as it may, even relatively “comprehensive” and “attractive” hypotheses do not provide an accurate description of exactly how the night star appeared on the earth’s horizon. However, such inconsistencies are observed when describing any other physical phenomenon of this scale, notes Alexander Rodin.

Every new discovery, even made under terrestrial conditions, can at any moment cast doubt on any “established” hypothesis in science. Even about the origin of the Earth - not to mention its satellite.

Nadezhda Serezhkina

> > > How the Moon was formed

Find out, how the moon appeared- the only satellite of the Earth. Description of theories of the creation of the Moon with photos: capture, large-scale impact and simultaneous appearance with the Earth.

After our star, the Sun, shed light, planets began to form. But the Moon decided to wait a few more million years. How was it formed? There are theories: a large-scale strike, simultaneous appearance and capture. Let's take a closer look at the history of the Moon.

Theories of Moon formation

Large-scale strike

This is the main idea that has the most supporters. The earth emerged from a cloud of dust and gas. At that time, the solar system was a real battlefield in which objects constantly collided, merged and changed orbit. One of them fell into the Earth, which had just formed.

The Mars-sized impact object is called Theia. During the collision, pieces of crust were separated from our planet. Gravity began to attract them until a complete object was formed. This explains why the Moon is made of lighter elements and is also less dense than the Earth. When the material concentrated around the remnants of Theia's core, it lingered near the plane of the Earth's ecliptic.

Joint formation

Planets and a satellite can form simultaneously. That is, gravity forced the pieces to condense and two objects were created in parallel. In this case, the satellite will have a composition similar to the planet and will be nearby. But the Moon is still less dense, which should not be the case if they appeared with the same heavy elements in the core.

Capture

Regarding the history of the Moon, there is an opinion that Earth’s gravity could grab a passing body (this was the case with the Martian Phobos and Deimos). The rocky body could have formed elsewhere in our system and was pulled into Earth's orbit. This theory explains the difference in composition. But there are also inconsistencies here, because usually such objects have a strange shape, and not spherical. And the orbital path is not built into the ecliptic.

Although the last two theories explain some points, they still ignore many important issues. Therefore, the first assumption is so far the best model for the appearance of the satellite. Now you know more about how the Moon came to be.

We are already accustomed to seeing the Moon in the sky. Most people believe that it has existed since the appearance of the Earth as our constant satellite, but the opinion of scientists, as well as some facts, make us think about this theory?

Was the Moon really always there as our natural satellite, or maybe it appeared later? Maybe it was even built?

I first read about the theory of an artificial moon as a child in the magazine “Science and Life”. When the Internet appeared, it became easier. This theory was developed and “coolly” substantiated many times by our Soviet scientists.

In 1968, an article appeared in the newspaper "Komsomolskaya Pravda", then in the magazine "Soviet Union", then a very serious study and scientific book by M.V. Vasiliev "Vectors of the Future" (Moscow, 1971). Works of scientists Khvastunov and Shcherbakov, a series of articles in Science and Life. In general, this was a very serious theory, which only slightly fell short of official recognition in the USSR and among the Americans.

So, in 1969, before the first astronaut Neil Armstrong landed on the Moon, used fuel tanks from unmanned spacecraft carrying out reconnaissance flights were dropped onto its surface. A seismograph was also left here then. Soon this device began transmitting information about vibrations of the lunar crust to Houston.

It turned out that the impact of a 12-ton load on the surface of our satellite caused a local “moonquake”. Many astrophysicists have suggested that beneath the rocky surface there was a metallic shell surrounding the Moon's core. Analyzing the speed of propagation of seismic waves in this supposedly metallic shell, scientists calculated that its upper boundary is located at a depth of about 70 kilometers, and the shell itself is approximately the same thickness.

Then one of the astrophysicists argued that inside the Moon there could be a huge, almost empty space with a volume of 73.5 million cubic kilometers.

This is how scientific facts emerged that the Moon is hollow. But what is even more interesting is that there is a lot of evidence and photographs of the mechanisms on the Moon that keep it running. Careful checks of these photographs have repeatedly confirmed their authenticity.
And this is only official science! And there is also theosophy, occult sciences...

If we look at how the Moon was depicted in ancient times, the mysteries will only increase. The Moon was depicted empty with the Gods inside it. I doubt that people back then had any idea what it was spaceship, and therefore they depicted it as they understood it within the framework of their ideas about the world.

Based on the available information, it can be argued that there were catastrophes on a planetary scale in the solar system, one of which “rebuilt” the solar system.

Perhaps Venus lost its satellite Mercury, and the Earth gained something? For example, the Moon?
After all, judging by the surviving data, before the great flood (which could have occurred just after a planetary catastrophe), there was no Moon in the sky in ancient times!

But if the Moon is not an artificial body, then how can the following facts be explained:

1. The incredible curvature of the moon's surface
2. Lunar craters are no deeper than 4 km, although the impact force of meteorites should have reached up to 50 km, which means the surface is very durable.
3. Geographic asymmetry. Location of the "lunar seas". 80% of them are on the visible side of the Moon while the "dark" side of the Moon has many more craters, mountains and landforms.
4. Gravity on the surface of the moon is not uniform
5. The density of our satellite is 60% of the density of the Earth. This fact along with various studies proves that the Moon is a hollow object.

The question arises. If the Moon is artificial, then why was it built?

All distances between planets in our solar system obey the Titius-Bode rule and are calculated using the formula that results in the following table:

It turns out that according to the formula there should be another planet after Mars, but in fact it is not there, but only the asteroid belt. This is how a very plausible theory emerged about the planet Phaeton, which once existed between Mars and Jupiter, but was then destroyed as a result of a tragedy on a cosmic scale.

Probably once there was a strong collision between a planet (I will conventionally call it a phaeton) and another cosmic body, as a result of which only an asteroid belt remained of the planet, its closest neighbor, Mars, lost its atmosphere (Scientists have come to the conclusion that Mars was once warm, humid and oxygen planet) and “frozen” (on Mars in ancient times there was water suitable for living organisms, and even now water has also been discovered)

In the textbook, in the section “formation of solar systems,” it says:

“Obviously, during a space disaster, which occurred as a result of the collision of two large cosmic bodies, a huge amount of debris was formed, scattering from the site of the disaster in different directions. Apparently, the planets at that time were located in orbit in such a way that Saturn was closest to the site of the disaster, which took on most of the debris. At the same time, Jupiter and Uranus also got something (depending on their position in orbit at that time).”

The Earth probably suffered too, given that it is located in front of Mars. Is this why there was a worldwide flood about which legends are made? You may not believe what is written in the Bible, but it turns out that references to the great flood are found in many cultures. Including, according to the research of J. J. Frazer, traces of legends with a similar plot were found in: Babylonia, Palestine, Syria, Armenia, Phrygia, India, Burma, Vietnam, China, Australia, Indonesia, the Philippines, the Andaman Islands, Taiwan, Kamchatka , New Guinea, the islands of Melanesia, Micronesia and Polynesia. Men in different places, even those people who have never seen the ocean in their lives preserve stories from generation to generation that speak of a global flood. What is this? Is it really a coincidence?

But there is also scientific and geological evidence of this event. Geology Ph.D. Terry Mortenson says:
1. We see fossils of sea animals on the highest mountains. In the Himalayas, in the Andes, in the rocky mountains. There are shell imprints everywhere. How did they get there? And how did they end up on the tops of the highest mountains?

2. Massive sedimentary deposits. We see this especially clearly in the Grand Canyon of the western United States. We see these sedimentary deposits all over the face of the earth. They are very thick, vast and sometimes stretch over tens of thousands of square kilometers. All this indicates that precipitation fell over a very large area at one time.

3. We see erosion in certain layers of the soil, which was much more intense than now. We see traces of erosion all over the surface of the earth. Cliffs, valleys. However, when we look at the layers of geological rocks, they look like a stack of pancakes. There are no traces of erosion between these layers...

In other words, there was a flood and it is quite possible that it was caused by the catastrophe that destroyed Phaeton. But even if we can prove one hundred percent that the Moon was made artificially, we will not answer the question: “Why was it necessary to make such a grandiose structure?” But you can think about this topic!

Let's consider the most possible options for the appearance of the Moon:

1) It was originally formed with the Earth. But if the Moon and Earth were formed together, simultaneously with the entire solar system, the Moon, like the Earth, should have more of an iron core;

2) This is one of the fragments of the destroyed planet, which was “pulled” by the Earth, but Earth’s gravity is not capable of attracting and holding such a large body as that of the Moon. Or the Earth collided at an angle of 23 degrees with something comparable in size to Mars. One way or another, as a result of the collision, we got the Moon. However, in some incomprehensible way it became hollow;

3) Using the principle of analogy, wheel balancing comes to mind. Let’s say you have new rims on your wheels that are perfectly balanced, but then there’s a hole in your way! Impact and now we have a bent disk whose center of gravity is shifted. Even for a wheel (14 inches), the imbalance is only 20 grams at a car speed of 100 km/h, in terms of loads it is equivalent to the blows of a sledgehammer weighing 3 kg hitting the wheel (taken from auto repair manuals), and then what can we say about the planet?
To level the center of gravity of the wheel, a special weight made of lead or zinc is used, which is attached to the wheel, adding weight.
Why not use the same principle to balance the motion of planets?

A catastrophe occurred, the orbits of some planets shifted. To align the orbits, Mercury was removed from Venus, and the Moon was added to Earth in the same way as wheel balancing is done, but only on a cosmic scale.

Someone (and therefore this someone exists and is clearly superior to people in technology and intelligence) specially selected its weight and placed it exactly where it is needed for the normal movement of the Earth, because as soon as the Moon is removed, the Earth will begin to rotate in arbitrary planes, it will lose stability, and its orbit will probably shift.

Someone specially built the Moon as a “weight” to align the Earth’s orbit and, moreover, still controls its position (so that nothing goes astray), keeps it from rotating (the Moon is always turned with one side towards the Earth), etc.

You can find many documentary videos on the Internet about the constant flights of UFOs both on the Moon itself and in various directions from and to the Moon

Someone constantly flies away from the Moon, then flies to it, flying inside the craters. Unknown structures and structures discovered on our satellite are more reminiscent of mechanical parts than natural formations.

There is another theory (supposedly coming from the Aryan Vedas), that at one time the Earth had three satellites, but then because of the war, two were blown up and only the Moon remained, as we know it. This version is widely discussed on the Internet. Supporters of this version would like to say the following:
1) You should always check your sources of information. If the Bible can still be referred to as a historical document that was written quite a long time ago, but when the Vedas were written is unknown. In general, the very existence of the Aryan Vedas is a mysterious thing, and the source is, to put it mildly, questionable. First published by the leader of the Old Believers sect A. Khinevich in 1990 and translated by him personally from a language that only he knows. Subsequently, Trekhlebov and the well-known guru of mysticism Levashov joined here.
2) The explosion of a satellite like the Moon in close proximity to the planet should, in theory, cause much worse consequences than a global flood
3) where are the fragments from the exploded 2 Moons flying in space? Or were they all pulled in by the Earth?

Well, which version do you like better?

We have already become accustomed to our only natural satellite, which tirelessly circles our planet every 28 days. The moon dominates our night sky, and since ancient times it has touched people's most poetic chords. Although new understandings of many lunar mysteries have been proposed over the past few decades, many unresolved questions still surround our only natural satellite.

Compared to other planets in our solar system, both the orbital path and size of our Moon are quite significant anomalies. Other planets, of course, also have satellites. But planets with weak gravitational influences, such as Mercury, Venus and Pluto, do not have them. The Moon is one quarter the size of the Earth. Compare this to the huge Jupiter or Saturn, which have several relatively small moons (Jupiter's moon is 1/80 its size), and our Moon seems to be a fairly rare cosmic phenomenon.

Another interesting detail: the distance from the Moon to the Earth is quite small, and in apparent size the Moon is equal to our Sun. This curious coincidence is most obvious during total solar eclipses, when the Moon completely obscures our nearest star.

Finally, the Moon's almost perfect circular orbit differs from the orbits of other satellites, which tend to be elliptical.

The gravitational center of the Moon is almost 1,800 m closer to the Earth than its geometric center. With such significant discrepancies, scientists still cannot explain how the Moon manages to maintain its almost perfectly circular orbit.

The gravitational attraction on the Moon is not uniform. The crew aboard Apollo VIII, while flying near the lunar ocean, noticed that the Moon's gravity had sharp anomalies. In some places, gravity seems to mysteriously increase.

The problem of the origin of the Moon has been discussed in the scientific literature for more than a hundred years. Its solution is of great importance for understanding the early history of the Earth, the mechanisms of formation of the Solar system, and the origin of life.

First a logical explanation for the origin of the Moon was put forward in the 19th century. George Darwin, son of Charles Darwin, author of the theory natural selection, was a famous and respected astronomer who carefully studied the Moon and in 1878 came up with the so-called separation theory. Apparently, George Darwin was the first astronomer to establish that the Moon was moving away from the Earth. Based on the speed of divergence of the two celestial bodies, J. Darwin suggested that the Earth and the Moon once formed a single whole. In the distant past, this molten viscous sphere rotated very quickly around its axis, making one full revolution in about five and a half hours.

Darwin suggested that the tidal influence of the Sun subsequently caused the so-called separation: a piece of molten Earth the size of the Moon separated from the main mass and eventually took its position in orbit. This theory looked quite reasonable and became dominant at the beginning of the 20th century. It only came under serious attack in the 1920s, when British astronomer Harold Jeffreys showed that the viscosity of the Earth in a semi-molten state would prevent vibrations strong enough to cause the two celestial bodies to separate.

Second theory, which once convinced a number of specialists, was called the accretion theory. It said that a disk of dense particles, reminiscent of the rings of Saturn, gradually accumulated around the already formed Earth. It was assumed that particles from this disk eventually came together to form the Moon.

There are several reasons why this explanation may not be satisfactory. One of the main ones is the angular momentum of the Earth-Moon system, which would never have become what it is if the Moon had formed from an accretion disk. There are also difficulties associated with the formation of oceans of molten magma on the “newborn” Moon.

Third theory about the origin of the Moon appeared around the time when the first lunar probes were launched; it is called the holistic capture theory. It was assumed that the Moon arose far from the Earth and became a wandering celestial body, which was simply captured by Earth's gravity and entered orbit around the Earth.

Now this theory has also fallen out of fashion for several reasons. The ratio of oxygen isotopes in rocks on Earth and the Moon strongly suggests that they formed at the same distance from the Sun, which could not have been the case if the Moon had formed elsewhere. There are also insurmountable difficulties in trying to construct a model in which a celestial body the size of the Moon could enter a stationary orbit around the Earth. Such a huge object could not carefully “float” to Earth at low speed, like a supertanker mooring to a pier; it almost inevitably had to crash into the Earth at high speed or fly next to it and rush on.

By the mid-1970s, all previous theories of the formation of the Moon had encountered difficulties for one reason or another. This created the almost unthinkable situation where renowned experts could publicly admit that they simply did not know how or why the Moon ended up where it did.

From this uncertainty was born new theory, which is now generally accepted, despite some serious issues. It is known as the "big impact" theory.

The idea originated in the Soviet Union in the 60s. from the Russian scientist B.C. Savronov, who considered the possibility of the emergence of planets from millions of asteroids of different sizes, called planetsimals.

In an independent study, Hartmann and his colleague D.R. Davis suggested that the Moon was formed as a result of the collision of two planetary bodies, one of which was the Earth, and the other was a wandering planet, not inferior in size to Mars. Hartmann and Davis believed that the two planets collided in a specific way, resulting in ejections of material from the mantle of both celestial bodies. This material was thrown into orbit, where it gradually combined and became denser to form the Moon.

New information obtained through detailed study of samples from the Moon has almost confirmed the collision theory: 4.57 billion years ago, the protoplanet Earth (Gaia) collided with the protoplanet Theia. The blow did not land in the center, but at an angle (almost tangentially). As a result, most of the substance of the impacted object and part of the substance of the earth's mantle were thrown into low-Earth orbit.

From these debris, the proto-Moon assembled and began to orbit with a radius of about 60,000 km. As a result of the impact, the Earth received a sharp increase in rotation speed (one revolution in 5 hours) and a noticeable tilt of the rotation axis.

In two new studies published in the latest issue of the journal Nature, scientists provide evidence that the chemical similarities between the Earth and the Moon are due to extensive mixing of material formed when the Earth collides with another planet.

Thus, supporters of the main theory of the origin of the earth’s satellite received new confirmation of their correctness, and quite significant ones at that. But, German scientists argue that other theories cannot simply be written off, since new data, although they seriously confirm the main theory, are still not one hundred percent. Therefore, there is still an opportunity to choose for yourself the closest theory of all existing ones, or even come up with a new one!