The satellite of the Earth has attracted the attention of people since prehistoric times. The moon is the most noticeable object in the sky after the sun, and therefore it has always been attributed to the same significant properties as the daylight. Over the centuries, worship and simple curiosity have been replaced by scientific interest. The waning, full and waxing moon are the objects of the most intent study today. Thanks to the research of astrophysicists, we know a lot about the satellite of our planet, but much remains unknown.
Origin
The moon is a phenomenon so familiar that the question of where it came from practically does not arise. Meanwhile, it is precisely the origin of the satellite of our planet that is one of its most significant secrets. Today there are several theories on this score, each of which boasts both the presence of evidence and arguments in favor of its inconsistency. The data obtained allow us to distinguish three main hypotheses.
- The Moon and Earth were formed from the same protoplanetary cloud.
- The fully formed Moon was taken over by the Earth.
- The collision of the Earth with a large space object led to the formation of the Moon.
Let's consider these versions in more detail.
Joint accretion
The hypothesis of the joint origin (accretion) of the Earth and its satellite was recognized in the scientific world as the most plausible until the early 70s of the last century. It was first put forward by Immanuel Kant. According to this version, the Earth and the Moon were formed almost simultaneously from protoplanetary particles. In this case, the cosmic bodies were a binary system.
The Earth was the first to form. After it reached a certain size, particles from the protoplanetary swarm began to circle around it under the influence of gravity. They began to move in elliptical orbits around the nascent object. Some particles fell to the Earth, others collided and stuck together. Then the orbit gradually began to approach more and more circular and from the swarm of particles the embryo of the Moon began to form.
Pros and cons
Today, the co-origin hypothesis has more rebuttals than evidence. It explains the identical oxygen-isotope ratio of the two bodies. The reasons put forward within the framework of the hypothesis for the different composition of the Earth and the Moon, in particular, the almost complete absence of iron and volatiles on the latter, are doubtful.
Guest from afar
In 1909, the hypothesis of gravitational capture was put forward by Thomas Jackson Jefferson C. According to her, the Moon is a body that was formed somewhere in another region of the solar system. Its elliptical orbit intersected the trajectory of the Earth's motion. At the next approach, the Moon was captured by our planet and became a satellite.
In favor of the hypothesis, scientists cite fairly widespread myths of the peoples of the world, telling about the time when the moon was not in the sky. Also indirectly, the theory of gravitational capture is confirmed by the presence of a solid surface on the satellite. According to Soviet studies, the Moon, which has no atmosphere, if it has been revolving around our planet for several billion years, should have been covered with a multi-meter layer of dust falling from space. However, today it is known that this is not observed on the surface of the satellite.
The hypothesis can explain the small amount of iron on the moon: it could have formed in the zone of giant planets. However, in this case, there must be a high concentration of volatile substances on it. In addition, according to the results of simulations of gravitational capture, its possibility seems unlikely. A body with the mass of the Moon would rather collide with our planet or be pushed out of orbit. Gravitational capture could only occur in the event of a very close passage of the future satellite. However, even in this variant, the destruction of the Moon under the influence of tidal forces becomes more probable.
Giant collision
The third of the above hypotheses is currently considered the most plausible. According to the giant collision theory, the Moon is the result of the interaction between the Earth and a rather large space object. The hypothesis was proposed in 1975 by William Hartman and Donald Davis. They suggested that a protoplanet named Theia collided with the young Earth, which managed to gain 90% of its mass. Its size corresponded to modern Mars. As a result of the impact that hit the "edge" of the planet, almost all of Teii's substance and part of the earth's was thrown into outer space. From this "building material" the Moon began to form.
The hypothesis explains the modern speed as well as the angle of inclination of its axis and many physical and chemical parameters of both bodies. The weak point of the theory is the reasons it cites for the low iron content on the Moon. For this, before the collision, complete differentiation had to occur in the bowels of both bodies: the formation of an iron core and a silicate mantle. To date, no evidence has been found. Perhaps new data on the earth's satellite will clarify this issue as well. True, there is a possibility that they can refute the hypothesis of the origin of the moon accepted today.
Main settings
For modern people, the moon is an integral part of the night sky. The distance to it today is about 384 thousand kilometers. This parameter changes somewhat as the satellite moves (the range is from 356 400 to 406 800 km). The reason lies in the elliptical orbit.
The satellite of our planet moves through space at a speed of 1.02 km / s. It makes a complete revolution around our planet in about 27.32 days (sidereal or sidereal month). Interestingly, the attraction of the moon by the sun is 2.2 times stronger than that of the earth. This and other factors affect the movement of the satellite: a decrease in the sidereal month, a change in the distance to the planet.
The moon's axis has an inclination of 88 ° 28 ". The rotation period is equal to a sidereal month, and that is why the satellite is always turned to our planet on one side.
Reflective
It can be assumed that the Moon is a star very close to us (in childhood, this idea could come to many). However, in reality, it does not have many of the parameters inherent in such bodies as the Sun or Sirius. So, sung by all romantic poets, moonlight is only a reflection of the sun. The satellite itself does not emit.
The phase of the moon is a phenomenon associated with the lack of its own light. The visible part of the satellite in the sky is constantly changing, successively passing through four stages: a new moon, a growing month, a full moon and a waning moon. These are the stages of the synodic month. It is calculated from one new moon to the next and lasts an average of 29.5 days. The synodic month is larger than the sidereal month, since the Earth also moves around the Sun and the satellite has to make up for some distance all the time.
Many faces
The first phase of the moon in the cycle is the time when there is no satellite in the sky for a terrestrial observer. At this time, it is facing our planet with a dark, unlit side. The duration of this phase is one to two days. Then a month appears in the western part of the sky. The moon is just a thin sickle at a time like this. Often, however, you can see the entire disk of the satellite, but less bright, colored gray. This phenomenon is called the ashen color of the moon. The gray disc next to the bright crescent is a portion of the satellite illuminated by rays reflected from the Earth's surface.
Seven days after the beginning of the cycle, the next phase begins - the first quarter. At this time, the moon is exactly half lit. A characteristic feature of the phase is a straight line dividing the dark and illuminated areas (in astronomy it is called the "terminator"). Gradually, it becomes more convex.
On the 14-15th day of the cycle, the full moon comes. Then the visible part of the satellite begins to decrease. On the 22nd day, the last quarter begins. During this period, an ashy color can also often be observed. The angular distance of the Moon from the Sun is set less and less, and after about 29.5 days, it completely disappears again.
Eclipses
Several other phenomena are associated with the peculiarities of the satellite's motion around our planet. The lunar orbital plane is tilted to the ecliptic by an average of 5.14 °. This situation is not typical for such systems. As a rule, the satellite's orbit lies in the plane of the planet's equator. The points of intersection of the trajectory of the Moon with the ecliptic are called ascending and descending nodes. They do not have an exact fixation, they constantly, albeit slowly, move. In about 18 years, the nodes pass the entire ecliptic. In connection with these features, the moon returns to one of them after a period of 27.21 days (it is called a draconian month).
With the passage of the satellite of the points of intersection of its axis with the ecliptic, such a phenomenon as an eclipse of the moon is associated. This is a phenomenon that rarely pleases (or grieves) us with itself, but has a certain periodicity. An eclipse occurs when the full moon coincides with the passage of a satellite of one of the nodes. Such an interesting "set of circumstances" occurs quite rarely. The same is true for the coincidence of the new moon and the passage of one of the nodes. At this time, a solar eclipse occurs.
Astronomers' observations have shown that both phenomena are cyclical. The length of one period is just over 18 years. This cycle is called saros. In one period, there are 28 lunar and 43 solar eclipses (of which 13 are total).
The influence of the night luminary
Since ancient times, the Moon has been considered one of the rulers of human destiny. According to thinkers of that period, it influenced character, attitudes, mood and behavior. Today, the effects of the moon on the body are being studied scientifically. Various studies confirm that the dependence of some characteristics of behavior and health status on the phases of the night luminary exists.
For example, doctors in Switzerland, who have been observing patients with problems in the cardiovascular system for a long time, have found that the waxing moon is a dangerous period for people prone to heart attacks. According to their data, most of the attacks coincided with the appearance of a young month in the night sky.
There are many similar studies. However, the collection of such statistics is not the only thing that interests scientists. They tried to find explanations for the revealed patterns. According to one of the theories, the Moon has the same effect on human cells as it does on the entire Earth: it causes As a result of the influence of the satellite, the water-salt balance, membrane permeability, and the ratio of hormones change.
Another version focuses on the influence of the moon on the magnetic field of the planet. According to this hypothesis, the satellite causes changes in the electromagnetic impulses of the body, which entails certain consequences.
Experts who are of the opinion about the enormous influence of the night star on us recommend that you build your activity, coordinating it with the cycle. They warn: lanterns and lamps that block moonlight can harm human health, because they prevent the body from receiving information about the phase change.
On the moon
After getting acquainted with the night star from the Earth, we will walk along its surface. The moon is a satellite that is not protected from exposure to sunlight by the atmosphere. During the day, the surface heats up to 110 ºС, and at night it cools down to -120 ºС. In this case, temperature fluctuations are typical for a small zone of the crust of a cosmic body. Very low thermal conductivity does not allow the satellite's interior to warm up.
We can say that the Moon is lands and seas, vast and little explored, but with their own names. The first maps of the satellite's surface appeared in the seventeenth century. The dark spots, previously considered seas, turned out to be low plains after the invention of the telescope, but they retained their name. The lighter areas on the surface are "continental" zones with mountains and ridges, often ring-shaped (craters). On the moon you can find the Caucasus and the Alps, the Seas of Crises and Tranquility, the Ocean of Storms, the Bay of Joy and the Swamp of Rot (the bays on the satellite are dark areas adjacent to the seas, swamps are small spots of irregular shape), as well as the Copernicus and Kepler mountains.
And only after that the far side of the moon was explored. It happened in 1959. The data obtained by the Soviet satellite made it possible to compile a map of the part of the night star hidden from the telescopes. The names of the greats also sounded here: K.E. Tsiolkovsky, S.P. Koroleva, Yu.A. Gagarin.
Quite another
The absence of an atmosphere makes the moon so unlike our planet. The sky here is never covered with clouds, its color does not change. There is only a dark star dome on the moon above the astronauts' heads. The sun rises slowly and moves slowly across the sky. A day on the moon lasts almost 15 earth days, and such is the length of the night. The day is equal to the period during which the satellite of the Earth makes one revolution relative to the Sun, or synodic month.
There is no wind and precipitation on the satellite of our planet, and there is also no smooth flow of day into night (twilight). In addition, the Moon is constantly under the threat of falling meteorites. Their number is indirectly evidenced by the regolith covering the surface. This is a layer of debris and dust up to several tens of meters thick. It consists of fragmented, mixed and in places fused remains of meteorites and lunar rocks destroyed by them.
When looking at the sky, you can see the Earth, still and always in the same place, hanging. A beautiful, but almost never changing picture is explained by the synchronization of the Moon's rotation around our planet and its own axis. This is one of the most wonderful spectacles that the astronauts who first landed on the surface of a satellite of the Earth have seen.
Famous
There are periods when the Moon is a "star" not only of scientific conferences and publications, but also of all kinds of media. Some rather rare satellite-related phenomena are of great interest to a large number of people. One of them is a super moon. It occurs on those days when the night star is at the smallest distance from the planet, and in the full moon or new moon phase. At the same time, the night light becomes visually 14% larger and 30% brighter. In the second half of 2015, the supermoon can be observed on August 29, September 28 (on this day, the supermoon will be the most impressive) and October 27.
Another curious phenomenon is associated with the periodic falling of the night luminary into the earth's shadow. In this case, the satellite does not disappear from the sky, but becomes red. The astronomical event was named the Blood Moon. This phenomenon is quite rare, but modern space lovers are lucky again. Blood Moons will rise over the Earth several times in 2015. The last of them will appear in September and coincide with the total eclipse of the night luminary. This is definitely worth seeing!
The night light has always attracted people to itself. The moon and the full moon are central images in many poetic essays. With the development of scientific knowledge and methods of astronomy, the satellite of our planet began to interest not only astrologers and romantics. Many facts from the time of the first attempts to explain the lunar "behavior" became clear, a large number of secrets of the satellite were revealed. However, the night star, like all objects in space, is not as simple as it might seem.
Even the American expedition was unable to answer all the questions posed to it. At the same time, every day scientists learn something new about the moon, although often the data obtained raise even more doubts about the existing theories. So it was with the hypotheses of the origin of the moon. All three main concepts that were recognized in the 60s and 70s were refuted by the results of the American expedition. Soon the giant collision hypothesis became the leading hypothesis. Most likely, in the future we will have many amazing discoveries associated with the night star.
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 a person has stepped 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 of the 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 ° С to +110 ° С. The force of attraction is 6 times less than that of the Earth (1.62 m / s2). Back in 1610, Galileo Galilei, in telescopic equipment, observed the lunar surface and discovered various depressions and craters.
Extended dark spots, or as they are called "Lunar seas", occupy about 40% of the visible lunar relief. In the olden days, attacks by meteorites and asteroids 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, we should say thank you for the fact that life on our planet has not disappeared, 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 have forever remained as a kind of reminder of the merits of our faithful satellite.
Moon structure
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 is composed of basalt rock. In marine and mainland 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 bowels is in a solid state, and is a cold and powerful lithosphere, with undamped seismic vibrations. Approaching the end of the lower mantle boundary, the temperature rises, approaching the melting temperature, 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 by one side, so everyone has long dreamed of knowing: what secrets are hidden by the reverse side of the Moon. By itself, the moon does not glow. It's just that the sun's rays, reflecting from the Earth, illuminate different parts of it. In this regard, the phases of the moon are also explained. It is turned to us with the dark side and moves in an orbit between the Sun and the Earth. There is a new moon every month. The next day, a bright crescent of the "renewed" moon appears in the western sky. On the rest of the Moon, the light reflected from the Earth practically does not fall. After a week, you can see half of the moon's disk. After 22 days, the last quarter is observed. And on the 30th day, the new moon comes again.
Moon characteristics
Mass: 0.0123 Earth masses, that is, 7.35 * 1022kg
Diameter at the equator: 0.273 times the diameter of the Earth, that is, 3476 km
Axis tilt: 1.55 °
Density: 3346.4 kg / m3
Surface temperature: -54 ° C
Distance from satellite to planet: 384,400 km
Speed of movement around the planet: 1.02 km / s
Orbital eccentricity: e = 0.055
Orbital inclination to ecliptic: i = 5.1 °
Free fall acceleration: g = 1.62 m / s2
Our planet, unlike many others, has only one natural satellite that can be observed at night in the sky - this, of course, is the Moon. If you do not take into account the Sun, then this particular object is the brightest that can be observed from Earth.
Among other satellites of the planets, the satellite of planet Earth is the fifth largest satellite. It has no atmosphere, no lakes or rivers. Day and night replace each other here with a frequency of two weeks, while a temperature drop of three hundred degrees can be observed. And she is always turned to us with only one side of her, leaving her dark back side in mysteries. This pale blue object in the night sky is the Moon.
The lunar surface is covered with a layer of regolith (black sand dust), which reaches a thickness from several meters to several dozen in different areas. Lunar sand regolith arises from the constant fall of meteorites and crushing in a state of vacuum, not protected by cosmic rays.
The surface of the Moon is uneven with many craters of various sizes. On the moon there are both plains and whole mountains, lined up in a chain, the height of the mountains is up to 6 kilometers. there is an assumption that more than 900 million years ago volcanic activity took place on the moon, this is evidenced by the found particles of soil, the formation of which could have been as a result of eruptions.
The surface itself on the Moon is very dark, despite the fact that on a moonlit night we can clearly see the Moon in the night sky. The lunar surface reflects just over seven percent of the sun's rays. Even from the Earth, one can observe spots on its surface, which, according to an ancient erroneous judgment, retained the name "sea".
Moon and planet earth
The moon is always facing the planet Earth with one side. On this side visible from the Earth, most of it is occupied by flat areas, which are called seas. The seas on the Moon occupy about sixteen percent of the total area and are giant craters that appeared after collisions with other cosmic bodies. The other side of the Moon, hidden from the Earth, is almost completely dotted with mountain ranges and craters from small to huge sizes.
The influence of the closest space object of the Moon extends to the Earth. So, a typical example is the ebb and flow of the seas, which arise due to the gravitational attraction of the satellite.
The origin of the moon
According to various studies, there are many differences between the Moon and the Earth, primarily in the chemical composition: there is practically no water on the Moon, a relatively low content of volatile elements, a low density in comparison with the Earth and a small core of iron and nickel.
Nevertheless, radiometric analysis, which determines the age of celestial objects if there is a radioactive isotope in the composition, showed that the age of the moon is the same as that of the earth, 4.5 billion years. The ratio of stable oxygen isotopes for two celestial objects coincides, despite the fact that for all the studied meteorites, such ratios have strong differences. This suggests that both the Moon and the Earth in the distant past were formed from one substance located at the same distance from the Sun in a pre-planetary cloud.
Based on the general age, a combination of similar properties with a strong difference between two close objects of the solar system, 3 hypotheses of the origin of the moon are put forward:
- 1. Formation of both the Earth and the Moon from one pre-planetary cloud
- 2. Capture by gravity of the Earth already formed object to the Moon
- 3. The formation of the Moon as a result of a collision with the Earth of a large space object comparable in size to the planet Mars.
The study of the pale blue satellite of the Earth, the Moon has been engaged since ancient times. For example, among the Greeks, the reflections of Archimedes on her are especially well known. Galileo described the Moon in detail with its characteristics and possible properties. He saw on the surface of the moon plains like "seas", mountains and craters. And in 1651, the Italian astronomer Giovanni Riccioli created a map of the Moon, where he painted in detail the lunar landscape of the surface visible from Earth and introduced designations for many parts of the relief of the Moon.
In the twentieth century, interest in the Moon increased with the help of new technological possibilities for exploring the Earth's satellite. So on February 3, 1966, the Soviet apparatus Luna-9 made a soft landing for the first time on the lunar surface. The next apparatus Luna-10 became the first artificial satellite of the Moon, and after a very short time, on July 21, 1969, a man first visited the Moon. There came a series of many discoveries in the field of selenography and selenology, which were made by Soviet scientists and their American colleagues from NASA. Then, by the end of the 20th century, interest in the moon gradually subsided.
(Photograph of the far side of the Moon, landing vehicle "Chanye-4")
The Chinese spacecraft "Chanye-4" on January 3, 2019 successfully landed on the surface of the far side of the moon, this side constantly facing away from the light emitted by the Earth and invisible from the surface of the planet. For the first time, the reverse side of the lunar surface was photographed by the Soviet station Luna-3 on October 27, 1959, and more than half a century later, at the beginning of 2019, the Chinese apparatus Chanye-4 landed on the surface opposite to the Earth.
Colonization on the Moon
Many writers and science fiction writers, along with the planet Mars, consider the Moon as an object for future human colonization. Despite the fact that it looks more like a fiction, the American agency NASA seriously thought about this issue, setting the task to develop a program "Constellation" to relocate people to the lunar surface with the construction of a real space base on the moon and the development of "inter-earth-lunar" space flights. However, this program was suspended by the decision of US President Barack Obama due to high funding.
Robot avatars on the moon
Nevertheless, in 2011, NASA again proposed a new program, this time called Avatars, which required the development and manufacture of robotic avatars on Earth, which would then be delivered to the Earth's satellite Moon in order to further simulate human life in lunar conditions. with the effect of telepresence. That is, a person will control the avatar-robot from Earth, fully dressed in a suit that will imitate his presence on the Moon as a robot-avatar, located in real conditions on the lunar surface.
Big moon illusion
When the Moon is low above the Earth's horizon, the illusion arises that its dimensions are larger than it actually is. At the same time, the real angular size of the Moon does not change, even, on the contrary, the closer it is to the horizon, the angular size decreases slightly. Unfortunately, this effect is difficult to explain and is more likely to be attributed to an error in visual perception.
Are there seasons on the moon?
Both on Earth and on any other planet, the change of seasons occurs from the tilt of its axis of rotation, while the intensity of the change of seasons depends on the location of the planet's orbital plane, whether it is a satellite around the Sun.
The moon, on the other hand, has an inclination of its axis of rotation to the plane of the ecliptic of 88.5 °, practically perpendicular. Therefore, on the moon, on the one hand, there is an almost eternal day, on the other hand, an almost eternal night. This means that the temperature in each part of the lunar surface is different and practically unchanged. At the same time, there can be no talk of changing the seasons on the moon, much more from the simple lack of atmosphere.
Why do dogs bark at the moon?
There is no unambiguous explanation for this phenomenon, but most likely, according to some scientists, the animal's fear of an effect similar to the solar eclipse from which many animals develop fear is playing. The sight of dogs and wolves is very weak and they perceive the moon on a cloudless night as the sun, confusing night with day. Weak moonlight and the moon itself are perceived by them as a dull sun and therefore, seeing the moon, they behave in the same way as during a solar eclipse, howling and barking.
Lunar capitalism
In Nikolai Nosov's fairytale novel "Dunno on the Moon", the Moon is a satellite, possibly of artificial origin, where inside there is a whole city - the bulwark of the modern capitalist system. Interestingly, the children's story seems not so much fantastic as it is socio-political that does not lose its relevance in modern times, interesting for both the child and the adult.
