Is the moon a planet? Where did the moon come from and what is it?

Earth's satellite since the prehistoric times attracted people's attention. The moon is the most visible object of the sky after the Sun, and therefore it has always been ascribed to it as significant properties as the daylight. Centuries later, scientific interest was replaced by worship and simple curiosity. The decreasing, full and growing Moon is today the objects of the closest study. Thanks to the research of astrophysicists, we know a lot about the satellite of our planet, but a lot remains unknown.

Origin

The moon is a phenomenon so familiar that there is practically no question of where it came from. Meanwhile, the origin of the satellite of our planet is one of its most significant secrets. Today, there are several theories on this subject, each of which can boast both the presence of evidence, and arguments in favor of its failure. The obtained data allow us to distinguish three main hypotheses.

1. The Moon and the Earth were formed from a single protoplanetary cloud.
2. The fully formed Moon was captured by the Earth.
3. The formation of the moon led to the collision of the Earth with a large space object.

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 1970s. For the first time it was put forward by Immanuel Kant. According to this version, the Earth and the Moon were formed almost simultaneously from protoplanetary particles. Cosmic bodies were a dual system.

The Earth began to form first. After it reached a certain size, particles of a protoplanetary swarm began to circulate around it under the influence of gravity. They began to move along elliptical orbits around the newly born object. Some particles fell to Earth, others collided and clumped together. Then the orbit gradually began to approach the circular one more and from the swarm of particles began to form the embryo of the Moon.

Pros and cons

Today the hypothesis of co-origin has more refutations than evidence. It explains the same oxygen-isotopic ratio of two bodies. Doubtful are the hypotheses put forward in the framework of the hypothesis of the different composition of the Earth and the Moon, in particular, the almost complete absence of the last iron and volatile substances.

Guest from afar

In 1909, Thomas Jackson, Jefferson C, put forward the hypothesis of gravitational capture. According to her, the Moon is a body formed somewhere in another area of the solar system. Its elliptical orbit crossed the trajectory of the Earth's motion. At the next rapprochement the Moon was captured by our planet and became a companion.

In favor of the hypothesis, the scientists cite fairly widespread myths of the peoples of the world, which tell of the time when the moon was not in the sky. Also indirectly, the theory of gravitational capture confirms the presence of a solid surface on the satellite. According to Soviet studies, the Moon, which has no atmosphere, if it rotates around our planet for several billion years, should have been covered with a multimeter of dust coming from space. However, today it is known that this is not observed on the surface of the satellite.

The hypothesis can explain a small amount of iron on the Moon: it could form in the zone of giant planets. However, in this case there should be a large concentration of volatile substances on it. In addition, according to the results of gravitational capture simulation, its possibility seems unlikely. A body with a mass like that of the Moon would rather collide with our planet or would be expelled from orbit. Gravitational capture could occur only in the case of a very close passage of a future satellite. However, 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 today considered to be the most plausible. According to the theory of a giant collision, the Moon is the result of the interaction of the Earth and a fairly large cosmic object. The hypothesis was proposed in 1975 by William Hartman and Donald Davis. They suggested that with the young Earth, which had already accumulated 90% of its mass, a protoplanet called Teya collided. Its size corresponded to modern Mars. As a result of the impact that came to the "edge" of the planet, almost all of the substance of the Tayy and part of the earth was thrown into outer space. From this "building material" began to form the Moon.

The hypothesis explains the current rotation speed of the Earth, 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 given by it for the low iron content on the Moon. For this, before the collision in the bowels of both bodies, a complete differentiation was to occur: the formation of an iron core and a silicate mantle. To date, no evidence has been found. Perhaps the new data on the Earth satellite will clarify this question. True, there is a possibility that they can also 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 varies somewhat as the satellite moves (range - from 356 400 to 406 800 km). The reason lies in an elliptical orbit.

The satellite of our planet moves through space at a speed of 1.02 km / s. The complete revolution around our planet, he makes about 27.32 days (sidereal or stellar month). It is interesting that the attraction of the Moon by the Sun is 2.2 times stronger than the Earth. This and other factors affect the motion of the satellite: reducing the sidereal month, changing the distance to the planet.

The axis of the moon has an inclination of 88 ° 28 '. The period of rotation is equal to the sidereal month and that is why the satellite is always turned to our planet by one side.

Reflective

We can assume 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 parameters inherent in such bodies as the Sun or Sirius. So, sung by all romantic poets, the 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, consistently passing through four stages: a new moon, a growing month, a full moon and a waning moon. This is the stage of the synodic month. It is calculated from one new moon to another and lasts an average of 29.5 days. The synodic month is more sidereal, because the Earth also moves around the Sun and the satellite has to catch up a certain distance all the time.

Many-faced

The first phase of the moon in the cycle is the time when there is no satellite in the sky for the terrestrial observer. At this time, he turned to our planet 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 only a thin sickle at such a time. Often, however, you can observe the entire disk of the satellite, but less bright, painted in gray. This phenomenon was called the ash color of the moon. The gray disk next to the bright sickle is part of the satellite, illuminated by rays reflected from the surface of the Earth.

Seven days from the beginning of the cycle, the next phase begins, the first quarter. At this time, the moon is illuminated exactly half. A characteristic feature of the phase is a straight line separating the dark and lighted area (in astronomy it is called the terminator). Gradually it becomes more convex.

On the 14-15 day of the cycle, a full moon comes. Then the visible part of the satellite begins to decrease. On day 22, the last quarter comes. During this period, it is also often possible to observe ash color. The angular distance of the Moon from the Sun is put ever less and after approximately 29.5 days it again completely disappears.

Eclipses

With the peculiarities of the motion of the satellite around our planet, several other phenomena are connected. The plane of the Moon's orbit is inclined to the ecliptic by an average of 5.14 °. This situation is not typical for such systems. As a rule, the orbit of the satellite lies in the plane of the equator of the planet. The points of intersection with the Moon's trajectory of the ecliptic are called ascending and descending nodes. They do not have an exact fixation, they move constantly, albeit slowly. In about 18 years, the nodes pass through 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 draconic month).

With the passage of the satellite points of intersection of its axis with the ecliptic is associated with such a phenomenon as the eclipse of the moon. This phenomenon is infrequent (or grieving) for us, but it has a certain periodicity. The eclipse occurs at the moment when the full moon coincides with the passage of the satellite of one of the nodes. Such an interesting "coincidence" is rare. The same is true for the coincidence of the new moon and the passage of one of the nodes. At this time, there is a solar eclipse.

Observations of astronomers have shown that both phenomena have a cyclic character. The length of one period is just over 18 years. This cycle is called the Saros. During one period 28 lunar and 43 solar eclipses take place (13 of them are total eclipses).

The influence of the night luminary

Since ancient times, Luna was considered one of the rulers of human destiny. According to the thinkers of that period, it influenced the character, attitudes, mood and behavior. Today, the action of the moon on the body is studied scientifically. Various studies confirm that the dependence of certain features of behavior and health status on the phases of the night luminary exists.

For example, Swiss doctors who have long observed patients with malfunctions in the cardiovascular system have established that the growing Moon is a dangerous period for people predisposed to heart attacks. Most of the seizures according to their data coincided with the appearance of a young month in the night sky.

There is a large number of similar studies. However, the collection of such statistics is not the only thing that scientists are interested in. They tried to find an explanation for the revealed patterns. According to one theory, the Moon has the same effect on human cells as it does on the whole Earth: it causes ebbs and tides. As a result of the influence of the satellite, the water-salt balance, the permeability of the membrane, the ratio of hormones change.

Another version focuses on the impact 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.

Specialists who hold opinions about the enormous influence of the night luminary on us recommend that they build their activities, coordinating it with the cycle. They warn: lanterns and lamps that block the moonlight can damage a person's health, because because of them the body does not receive information about the phase change.

On the moon

After getting acquainted with the night light 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. In the daytime the surface heats up to 110 ºС, and at night it cools down to -120 ºС. In this case, temperature fluctuations are characteristic of a small zone of the crust of the cosmic body. Very low thermal conductivity does not allow to warm up the bowels of the satellite.

It can be said that the Moon is a land and a sea, vast and little explored, but possessing their own names. The first maps of the surface of the satellite appeared in the seventeenth century. Dark spots, previously taken over the seas, after the invention of the telescope turned out to be low plains, but 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 Sea 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 adjoining the seas, the marshes are small spots of irregular shape), and the mountains of Copernicus and Kepler.

And only after the beginning of the space age was the back side of the moon explored. This happened in 1959. The data received by the Soviet satellite, allowed to make a map hidden from the telescopes of a part of the night luminary. Here also the names of the great ones were heard: KE. Tsiolkovsky, S.P. Queen, Yu.A. Gagarin.

Quite another

The absence of an atmosphere makes the moon so unlike our planet. The sky is never clouded here, its color does not change. On the moon above the cosmonauts' head only a dark star dome. The sun rises slowly and unhurriedly moves across the sky. The day on the Moon lasts for almost 15 terrestrial days, so is the duration of the night. The day is equal to the period for which the Earth's satellite makes one revolution relative to the Sun, or the synodic month.

On the satellite of our planet there is no wind and rain, and also there is no smooth overflow of the day into the night (twilight). In addition, the Moon is constantly under the threat of falling meteorites. Regolith, covering the surface, indirectly indicates their quantity. It is a layer of debris and dust up to several tens of meters in thickness. It consists of fragmented, intermixed and locally fused remains of meteorites and the lunar rocks destroyed by them.

When you look at the sky you can see motionless and always in the same place hanging the Earth. A beautiful, but almost never changing picture is explained by the synchronization of the rotation of the moon around our planet and its own axis. This is one of the most wonderful spectacles that happened to see cosmonauts, first landed on the surface of the satellite of the Earth.

Famous

There are periods when the Moon is a "star" of not only scientific conferences and publications, but also all kinds of media. Of great interest to a large number of people are some rather rare phenomena associated with the satellite. One of them is the super moon. It occurs in those days when the night star is at the smallest distance from the planet, and in the phase of a full moon or a new moon. The night star becomes visually 14% larger and 30% brighter. In the second half of 2015, the super moon will be observed on August 29, September 28 (on this day the super moon will be the most impressive) and on October 27.

Another curious phenomenon is associated with the periodic fall of the night star into the earth's shadow. The satellite does not disappear from the sky, but gets red. The astronomical event was called the Blood Moon. This phenomenon is quite rare, but modern amateurs of space are again fortunate. The Blood Moon will rise over the Earth in 2015 several times. The last of them will appear in September and will coincide with a total eclipse of the night luminary. This is definitely worth seeing!

The night star always attracted people. A month and a full moon are central images in many poetic essays. As the scientific knowledge and methods of astronomy developed, the satellite of our planet became interested not only in astrologers and romantics. Many facts since the first attempts to explain the lunar "behavior" have become clear, a large number of satellite secrets have been revealed. However, the night star, like all objects of the cosmos, is not as simple as it may seem.

Even the American expedition failed to answer all the questions posed to it. At the same time, scientists are learning something new about the Moon every day, although often the data obtained give rise to even more doubts in the existing theories. So it was with the hypotheses of the origin of the moon. All three main concepts, which were recognized in the 60-70's, were disproved by the results of the American expedition. Soon, the hypothesis of a giant collision became the leading one. Most likely, in the future we will have many amazing discoveries related to the night light.