What speed is the asteroid in space flies. Meteorites falling on the ground: a gift for universe or cosmic destroyers? Meteorites that have fallen on our planet

In the previous post, an assessment of the danger of an asteroid threat from space was given. And here we will consider what will happen if (when) a meteorite of one or another will fall to the ground.

The scenario and the consequences of such an event as a fall on the Earth of the cosmic body, of course depends on many factors. We list the main:

Size of the Space Body

This factor is naturally priority. Armageddon on our planet can arrange a meteorite of kilometers in 20, so in this post we consider the scenario of falling on the planet of cosmic bodies of the dust size up to 15-20 km. More - it makes no sense, since in this case the script will be simple and obvious.

Structure

Small solar bodies can have a different composition and density. Therefore, there is a difference, whether a stone or iron meteorite will fall to the ground, or a loose, consisting of ice and snow core comet. Accordingly, to apply the same destruction, the comet kernel should be two or three times more than the sharp of the asteroid (at the same rate of fall).

For reference: more than 90 percent of all meteorites are stone.

Speed

Also a very important factor in the collision of tel. After all, there is a transition of the kinetic energy to thermal. And the rate of entry of cosmic bodies into the atmosphere may vary at times (approximately from 12 km / s to 73 km / s, comet is even more).

The most slow meteorites are catching up the land or catching it. Accordingly, flying to us to meet their speed with the orbital speed of the Earth, it will be much faster through the atmosphere, and the explosion from their impact on the surface will be more powerful.

Where falls

In the sea or on land. It is difficult to say in which case of destruction will be more, just everything will be different.

The meteorite can fall into the storage location of nuclear weapons or nuclear power plant, then harm to the environment may be more from contamination with radioactive substances than from the impact of the meteorite (if it was relatively small).

Angle of incidence

The big role does not play. With those huge speeds in which the cosmic body is crashed into a planet, it does not matter how an angle it falls, since in any case the kinetic energy of the movement will switch to thermal and will be released as an explosion. From the angle of the fall, this energy does not depend, but only from the mass and speed. Therefore, by the way, all crater (on the moon, for example) have a circular shape, and there are no crater in the form of some drilled trenches.

How do bodies of different diameters behave when falling to the ground

Up to several centimeters

Completely burned in the atmosphere, leaving a bright track length of several tens of kilometers (well-known phenomenon called meteor). The largest of them arrive to heights of 40-60 km, but most of these "dust" burn at an altitude of more than 80 km.

Mass phenomenon - for only 1 hour in the atmosphere, millions (!!) meteors flashed. But, taking into account the brightness of the outbreaks and the radius of the observer review, at night in one hour you can see from several pieces to dozen meteors (during meteoric flows - more than a hundred). During the day, the mass of dust from meteors onto the surface of our planet from meteors is calculated in hundreds, and even in thousands of tons.

From centimeters to several meters

Bollians - The most bright meteors, the brightness of the outbreak of which exceeds the brightness of the Venus planet. The flash may be accompanied by noise effects up to the sound of the explosion. After that, a smoky trace remains in the sky.

The fragments of cosmic bodies of this size reaches the surface of our planet. This happens like this:

At the same time, stone meteoroids and the more icy, from the explosion and heating are usually crushed into fragments. Metal can withstand pressure and fall to the surface entirely:

Iron meteorite "Goba" in size about 3 meters, which fell "entirely" 80 thousand years ago on the territory of modern Namibia (Africa)

If the speed of entry into the atmosphere was a very large (counter trajectory), then such meteoroids have a much less chance to fly to the surface, since the strength of their friction about the atmosphere will be much larger. The number of fragments to which the meteoroid is crushed to hundreds of thousands, the process of their fall is called meteor Rain.

During the day, several dozen small (about 100 grams) of meteorites (about 100 grams) of meteorites can fall over the day in the form of cosmic precipitation. Taking into account the fact that most of them fall into the ocean, and in general, they are difficult distincts from ordinary stones, they find them quite rarely.

The number of entries into our atmosphere of cosmic bodies of the size of a meter is several times a year. If you are lucky, and the fall in such a body will be seen, there is a chance to find decent fragments weighing hundreds of grams, and even in kilograms.

17 meters - Chelyabinsk Bolide

Superbolid - It is sometimes called particularly powerful explosions of meteoroids, similar to what exploded in February 2013 over Chelyabinsk. The initial size included then into the atmosphere of the body on various expert estimates varies, on average it is estimated at 17 meters. Mass - about 10,000 tons.

The facility entered the atmosphere of the Earth under a very sharp angle (15-20 °) at a speed of about 20 km / s. He exploded after half a minute at a height of about 20 km. The power of the explosion was somewhat hundreds of kilotonne in TNT equivalent. It is 20 times more powerful than the Hiroshima bomb, but here the consequences were not so fatal because the explosion occurred at high altitude and the energy was dissipated in a large area, largely away from settlements.

To the Earth, less than a tenth part of the initial mass of the meteoroid, that is, about a ton or less. Shards scattered through an area of \u200b\u200bmore than 100 long, and a width of about 20 km. A lot of small fragments were found, a few weight per kilograms, the largest piece weighing 650 kg was raised from the bottom of Lake Chebarkul:

Damage: Almost 5,000 buildings were injured (mostly knocked out windows and frames), the fragments of Stekol pledged about 1.5 thousand people.

The body of this size could well achieve the surface without lounging on the fragments. This did not happen because of the too acute corner of the entrance, because before exploding, the meteoroid flew in the atmosphere several hundred kilometers. If the Chelyabinsk meteoroid fell vertically, then instead of an air shock wave, which beat a glass, there would be a powerful blow to the surface, which had the seismic push, with the formation of a crater with a diameter of 200-300 meters. On the damage and number of victims, in this case, judge themselves, everything would depend on the place of fall.

Concerning frequency repetition Such events, then after the Tungusian meteorite of 1908, this is the largest celestial body fell on the ground. That is, in one century you can expect one or more of these guests from space.

Tens of meters - Small asteroids

Children's toys are over, go to more serious things.

If you read the previous post, you know that the small bodies of the solar system of up to 30 meters are called meteoroids, more than 30 meters - asteroids.

If the asteroid, even the smallest will meet with the earth, then he will definitely fall asleep in the atmosphere and its speed will not slow down to the speed of free fall, as it happens with meteoroids. All the huge energy of his movement will be released in the form of an explosion - that is, will switch to thermal energywhich melts the asteroid itself and mechanicalwhich will create a crater, scatters around the earth's breed and fragments of the asteroid itself, and will also create a seismic wave.

To quantify the scale of such a phenomenon, it is possible to consider an asteroid crater in Arizona:

This crater was formed 50 thousand years ago from the impact of the iron asteroid with a diameter of 50-60 meters. The explosion force was 8,000 Hirosim, the diameter of the crater is 1.2 km, the depth is 200 meters, the edges rise above the surrounding surface by 40 meters.

Another comparable event is a Tungusian meteorite. The explosion capacity was 3000 Hiroshim, but there was a drop in a small nucleus of a comet with a diameter of tens to hundreds of meters by different estimates. Kernel Comets often compare with dirty snowy cakes, so in this case no crater arose, the comet exploded in the air and evaporated, writing the forest on the territory of 2 thousand square kilometers. If the same comet exploded over the center of modern Moscow, she would destroy all at home to the ring road.

Fall frequency Asteroids in the size of tens of meters - once a few centuries, hundred meters - once every few thousand years.

300 meters - asteroid apophis (the most dangerous of those known at the moment)

Although according to the latest NASA data, the likelihood of an Asteroid asteroid "Apophis" with it near our planet in 2029, and then in 2036 almost equal to zero, still consider the scenario of the consequences of its possible fall, since there are many not open asteroids, and A similar event still can occur, not in this one, the other time.

So .. asteroid Apophis contrary to all forecasts falls on the ground ..

The power of the explosion is 15,000 Hiroshimian atomic bombs. When inserted into the mainland, a shock crater arises with a diameter of 4-5 km and a depth of 400-500 meters, the shock wave is demolished all the brick buildings in the zone of 50 km with a radius of 50 km, less durable buildings, as well as trees lying at a distance of 100-150 kilometers from the place Falls. In the sky, the dust will rise like a mushroom with a nuclear explosion with a height of a few kilometers, then the dust begins to spread in different directions, and within a few days it is uniformly spread across the planet.

But, in spite of the highly exaggerated horns, which usually scare people media, nuclear winters and the end of the world will not come - the Caliber "Apophis" is not enough for this. According to the experience of having a place in a not very longstanding history of high-power eruptions of volcanoes, under which huge emissions of dust and ash in the atmosphere also occur, with such an explosion power, the effect of "nuclear winter" will be small - the drop in the average temperature on the planet for 1-2 degrees, through For half a year - a year everything returns to its places.

That is, it is a catastrophe not global, but a regional scale - if Apophis falls into a small country, he will destroy it completely.

When apophis in the ocean, coastal areas will suffer from tsunami. The height of the tsunami will depend on the distance to the fall place - the initial wave will have a height of about 500 meters, but if Apophis falls to the center of the ocean, then 10-20 meter waves will reach the shores, which is also a lot, and the storm with such mega- Waves will be several hours. If the blow to the ocean will occur not far from the coast, then the siefs in coastal (and not only) cities will be able to ride such a wave: (sorry for the black humor)

The frequency of repetition Events of this scale in the history of the Earth is measured in tens of thousands of years.

Go to global catastrophes ..

1 kilometer

The scenario is the same as in the fall of Apophis, only the scale of the consequences are more serious and already reaching the global catastrophe of the low threshold (the consequences feels all humanity, but there is no threat of death of civilization):

The power of the explosion in "Hiroshima": 50000, the size of the resulting crater when falling per landing: 15-20 km. The radius of the zone of destruction from the explosive and seismic wave: up to 1000 km.

When falling into the ocean, again, it all depends on the distance to the coast, since the waves that have arisen will be very high (1-2 km), but not long, and such waves fade quite quickly. But in any case, the area of \u200b\u200bflooded territories will be huge - millions of square kilometers.

A decrease in the transparency of the atmosphere in this case from the emissions of dust and ashes (or water vapor when falling into the ocean) will noticeably for several years. If you get into the seismically dangerous zone, the consequences can be aggravated by a convicted explosion of earthquakes.

However, any noticeably tilt the earth axis or influence the period of rotation of our planet asteroid of this diameter will not be able.

Despite all the dramaticness of this scenario, for the Earth, this is a fairly ordinary event, as it has already happened for thousands throughout its existence. The average frequency of repetition - Once in 200-300 thousand years.

Asteroid with a diameter of 10 kilometers - global planetary scale catastrophe

The power of the explosion in "Hiroshima": 50 million
The size of the resulting crater when falling per landing: 70-100 km, depth - 5-6 km.
The depth of cracking of the earth's crust will be tens of kilometers, that is, up to the mantle (the thickness of the earth's crust under the plains is an average of 35 km). Magma will begin on the surface.
The area of \u200b\u200bdestruction zone can be several percent of the land area.
In the explosion, the cloud of dust and molten rock will rise to the height of tens of km, possibly - up to hundreds. The volume of discharged materials is several thousand cubic kilometers - this is sufficient for light "asteroid autumn", but not enough for the "asteroid winter" and the beginning of the ice age.
Secondary craters and tsunami from fragments and large pieces of thrown out.
Small, but in geological standards, a decent slope of the earth's axis from the blow - to 1/10, the share of degrees.
If you get into the ocean - tsunami with kilometer (!!) waves going far deep into the mainland.
In the case of intensive eruptions of volcanic gases, acid rains are possible.

But it is still not quite Armageddon! Even such ambitious catastrophes our planet has already experienced dozens or even hundreds of times. On average, this happens one once every 100 million years. This is currently happening, the number of victims would be unprecedented, in the worst case it could be measured in billions of people, besides, it is not known what social shocks would be led. However, despite the period of acid rain and several years of some cooling due to a decrease in the transparency of the atmosphere, after 10 years, the climate and the biosphere would be completely restored.

Armageddon

For such a significant event in the history of mankind, an asteroid size is required 15-20 kilometers in the amount of 1 thing.

The next glacial period will come, most of the living organisms will die, but life on the planet will continue, although no longer be such as before. As usual, the strongest will survive ..

Such events have just repeatedly happened at the occurrence of life on it, Armageddons occurred at least somewhat, and perhaps dozens of times. It is believed that the last time it happened 65 million years ( Chiksulubsky meteorite) When dinosaurs died and almost all other types of living organisms, only 5% of favorites remained, including our ancestors with you.

Full Armagedets

If the Space body of Texas dwells into our planet, as was in a famous film with Bruce Willis, then even bacteria will not survive (although, who knows them?), Life will have to arise and evolve again.

Output

I wanted to write a review of the post about meteorites, and the scenarios of Armageddon turned out. Therefore, I want to say that all described events starting with Apophis (inclusive) are considered as theoretically possible, since in the next few years they will definitely not happen. Why is it so detailed in the previous post.

I also want to add that all the numbers listed here, regarding the correspondence of the size of the meteorite and the consequences of its fall to the ground, are very approximate. The data in different sources differ, plus the initial factors in the fall of the asteroid of the same diameter can vary very much. For example, everywhere it is written that the size of the ChicSulubsk meteorite is 10 km, but in one, as it seemed to me, I could not have a reputable source that a 10-kilometer stone would not have been able to do, so I had a chiksulubsk meteorite in 15-20 kilometer category .

So, if suddenly Apophis falls all the same in the 29th or 36th year, and the radius of the lesion zone will be very different from what is written here - write, correct

However, in space everything is different, some phenomena are simply inexplicable and no laws are presented in principle. For example, a satellite launched several years ago, or other objects will rotate in their orbit and never fall. Why is this happening, how fast is the rocket in space? Physics suggest that there is a centrifugal force that neutralizes the effect of gravity.

Having done a small experiment, we can ourselves without leaving the house, it is understood and sense. To do this, take a thread and tie to one end a small cargo, further spinning the thread around the circle. We will feel that the higher the speed, the trajectory at the load will be more clear, and the thread is stretched more, if weaken the power, the speed of rotation of the object will decrease and the risk that the cargo falls, increases several times. Here, with such a small experience, we will start developing our topic - speed \u200b\u200bin space.

It becomes clear that high speed allows any object to overcome the force of attraction. As for space objects, everyone has their own speed, it is different. The four main types of such velocity are determined and the smallest one is the first. It is at such a speed that the ship is flies into orbit.

In order to fly beyond its limits. speed \u200b\u200bin space. At the third speed, completely overcomes and can be departed beyond the limits of the solar system. Fourth rocket speed in space Let me leave the galaxy itself, it is about 550 km / s. We have always been interesting rocket speed in space KM H,when entering orbit, it equals 8 km / s, beyond its limits - 11 km / s, that is, developing its capabilities up to 33,000 km / h. The rocket increases gradually speed, high-grade acceleration begins with a height of 35 km. Speed Cosmos exit It is 40,000 km / h.

Speed \u200b\u200bin Space: Record

Maximum speed in space - The record set 46 years ago, still keeps, he was made by astronauts who took part in the "Apollo 10" mission. Wearing the moon, back they returned when space ship speed in space Mounted 39,897 km / h. In the near future, it is planned to be sent to the space of the university "Orion" ship, which will bring astronauts to a low near-earth orbit. It may be possible to beat the 46-year-old record. Speed \u200b\u200bof light in space - 1 billion km / h. Interestingly, can we overcome such a distance with our maximum speed of 40,000 km / h. Here what speed in space It develops at the light, but we do not feel it here.

Theoretically, a person can move at a speed of a slightly lower speed of light. However, this will entail tremendous harm, especially for an unprepared organism. After all, to begin with such speed you need to develop, make an effort to reduce it safely. Because rapid acceleration and slowdown can become fatal for humans.

In ancient times it was believed that the land was still not interested, no one was interested in the rate of her rotation in orbit, because such concepts did not exist in principle. But now it is difficult to give an unequivocal answer to the question, because the value is unequal in different geographic points. Closer to the equator speed will be higher, in the area of \u200b\u200bthe south of Europe, it equals 1,200 km / h, so the average earth speed in space.

Cosmos is a space filled with energy. The forces of nature are forced, chaotic existing matter to be grouped. Objects are formed with a specific form and structure. In the solar system, planets have long been formed, their satellites, but this process does not end. A huge amount of substance: dust, gas, ice, stone and metal, fill space. These objects have a classification.

The body of the size of no more than a dozen meters is called the meteoroid larger body can be considered asteroid. Meteor is a combining object in the atmosphere, falling on the surface becomes a meteorite.

In the solar system, hundreds of thousands of asteroids are open. Some achieve more than 500 kilometers in diameter. Massows of large sizes take a spherical shape and begin to be classified by scientists like dwarf planets. The speed of asteroids is limited by the presence in the solar system, they rotate around the sun. Pallada is currently considered the largest asteroid, 582 × 556 × 500 km. It has an average rate of 17 kilometers per second, asteroids developed by asteroids does not exceed this value more than two times. The name of the asteroids is the date of their opening (1959 LM, 1997 VG). After studying, calculating the orbit object can get its own name.

Heavenly bodies inevitably face each other. The moon retained the result of millions and millions of years of interaction. On earth, huge craters say that there have once been global destruction. People always strive for control, all potential threats should have methods, technology to their elimination. The obvious option using nuclear weapons is inffective. Most of the explosion energy simply dissipates in space. It is extremely important to detect a dangerous bluing as early as possible, which is not always obtained. Good thing is that the more body, the easier it is to detect it.

A ton of cosmic dust flies into the atmosphere every day, at night you can observe how small meteoric bodies burn out, the so-called "falling stars". Each year of meteoroids of up to several meters fall into the airspace of our planet. The meteorite can enter the atmosphere at a speed of 100,000 km / h. At the height of several tens of kilometers, speed drops sharply. In general, information about the speed of meteorites is blurred. Limits from 11 to 72 kilometers per second for the meteorites of the solar system, flying from the outside develop an order of magnitude greater speed.

On February 15, 2013, a meteorite fell in the Chelyabinsk region. Presumably his diameter was from 10 to 20 meters. The meteorite speed is definitely not defined. The bright glow of the car was observed for hundreds of kilometers from the epicenter. The car exploded at high altitude. The video captured the flash, after 2 minutes. 22 sec. The shock wave comes.

Meteorites are divided into stone and iron. The composition always includes a mixture of elements with a variety of proportional ratios. The structure may be inhomogeneous with inclusions. Metal alloy of iron meteorites of excellent quality is suitable for the manufacture of all sorts of products.

3. Flight of meteors in the earth's atmosphere

Meteors appear at 130 km altitudes and below and usually disappear near the height of 75 km. These boundaries vary depending on the mass and speed of meteoric bodies penetrating into the atmosphere. Visual determinations of the heights of meteors from two or more points (the so-called corresponding) refer mainly to meteors of the 0-3rd star magnitude. Taking into account the influence of rather significant errors, visual observations give the following meanings of meteors: the height of the appearance H 1. \u003d 130-100 km, extinction height H 2. \u003d 90 - 75 km, middle path height H 0. \u003d 110 - 90 km (Fig. 8).

Fig. 8. Heights ( H.) Meteoric phenomena. Limits of heights (Left): The beginning and end of the path of the car ( B.), meteors on visual observations ( M.) and radar observations ( RM.), telescopic meteors on visual observations ( T.); (M. T.) - the area of \u200b\u200bdelay meteorites. Curves distribution (on right): 1 - the middle of the meteors on radar observations, 2 - the same in photographic data 2A. and 2B - The beginning and end of the path in photographic data.

Much more accurate photographic definitions of heights include, as a rule, to a brighter meteor, from -5 to the 2nd star magnitude, or to the most striking areas of their trajectories. According to photographic observations in the USSR, the height of bright meteors consist in the following limits: H 1. \u003d 110-68 km, H 2. \u003d 100-55 km, H 0 \u003d 105-60 km. Radar observations allow you to determine separately H 1. and H 2. Only for the most striking meteors. By radar data for these objects H 1. \u003d 115-100 km, H 2. \u003d 85-75 km. It should be noted that the radar determination of the height of meteors only applies to the part of the meteor trajectory, along which a fairly intensive ionization mark is formed. Therefore, for the same meteor, the height in photographic data may differ significantly from the height of radar data.

For weaker meteors, with the help of the radar, it is possible to determine statistically only the average height. The distribution of the average heights of meteors is predominantly the 1-6th stars obtained by the radar method, shown below:

Considering the actual material to determine the heights of meteors, it is possible to establish that according to all this data, the vast majority of these objects are observed in a height zone of 110-80 km. In the same zone, telescopic meteors are observed, which by A.M. Bakhareva have heights H 1. \u003d 100 km, H 2. \u003d 70 km. However, by telescopic observations I.S. Astapovich and his employees in Ashgabat a significant number of telescopic meteors are also observed below 75 km, mainly at 60-40 km altitudes. This, apparently, slow and therefore weak meteors that begin to glow, only deeply crashed into the earth's atmosphere.

Turning to very large objects, we find that the barns appear at altitudes H 1. \u003d 135-90 km, having the height of the end point of the path H 2. \u003d 80-20 km. The accompanies penetrating the atmosphere below 55 km are accompanied by sound effects, and the reaches of 25-20 km are usually preceded by the fallout of meteorites.

The heights of meteors depend not only on their mass, but also on the speed of them relative to the Earth, or the so-called geocentric speed. The greater the meteor speed, the higher it begins to glow, since the fast meteor even in a rarefied atmosphere is much more often faced with air particles than a slow. The average height of meteors depends on their geocentric velocity as follows (Fig. 9):

Geocentric speed ( V G.)	20	30	40	50	60	70 km / s
Average height ( H 0.)	68	77	82	85	87	90 km

With the same geocentric velocity of meteors, their height depend on the mass of the meteor body. The greater the mass of the meteor, the lower it penetrates.

The visible part of the meteor trajectory, i.e. The length of its path in the atmosphere is determined by the meanings of the heights of its appearance and disappearance, as well as the inclination of the trajectory to the horizon. The steeper the slope of the trajectory to the horizon, the shorter the visible length of the path. The length of the path of ordinary meteors does not exceed, as a rule, several tens of kilometers, but for very bright meteors and the car it reaches hundreds, and sometimes thousand kilometers.

Fig. 10. Anti-aircraft attraction of meteors.

Meteors are glowing on a short visible segment of their trajectory in the earth's atmosphere stretching several tens of kilometers, which they fly over a few tenths of a second (less often in a few seconds). On this segment of the meteor trajectory, the action of the land and braking in the atmosphere is already manifested. When approaching the Earth, the initial meteor velocity under the action of the earth's attraction increases, and the path is being twisted in such a way that the observed radiant is shifted to the zenith (Zenit is a point above the observer head). Therefore, the effect of attraction of the Earth on meteoric bodies is called anti-aircraft attraction (Fig. 10).

The slower meteor, the greater the influence of the zenith attraction, as can be seen from the following plate, where V. g. denotes the initial geocentric speed, V " g. - the same speed distorted by the attraction of the Earth, and Δz.- Maximum value of zenith attraction:

V. g.	10	20	30	40	50	60	70 km / s
V " g.	15,0	22,9	32,0	41,5	51,2	61,0	70.9 km / s
Δz.	23 O.	8 O.	4 O.	2 O.	1 O.	<1 o

Penetrating into the atmosphere of the Earth, the meteoric body is experiencing, in addition, braking, first almost imperceptible, but very significant at the end of the path. According to Soviet and Czechoslovatsky photographic observations, braking can reach 30-100 km / sec. 2, at the same time, along a large part of the trajectory, braking ranges from 0 to 10 km / s 2. Slow meteors are experiencing the greatest relative loss of speed in the atmosphere.

The seeming geocentric speed of meteors, distorted by anti-aircraft attraction and braking, is appropriately corrected, taking into account the influence of these factors. For a long time, meteor velocities were not known exactly because they were determined from minor visual observations.

The photographic method for determining the speed of meteors with the use of the obturator is the most accurate. All without exception to determine the speed of meteors, obtained by photographic in the USSR, Czechoslovakia and the United States, show that meteoric bodies must move around the sun on closed elliptic paths (orbits). Thus, it turns out that the overwhelming part of the meteorful matter, if not the whole, belongs to the solar system. This result is perfectly consistent with the data of radar definitions, although photographic results are on average to brighter meteors, i.e. to larger meteoric bodies. Meteor's velocity distribution curve, found using radar observations (Fig. 11), shows that the geocentric velocity of meteors is mainly ranging from 15 to 70 km / s (some quantity definitions superior to 70 km / s are due to the inevitable observation errors ). This once again confirms the conclusion that meteoric bodies move around the Sun on the ellipses.

The fact is that the speed of the earth in orbit is 30 km / s. Therefore, counter meteors having a geocentric speed of 70 km / s are moving relative to the sun at a speed of 40 km / s. But at the distance of the Earth, parabolic speed (i.e., the speed required so that the body is carved by parabole outside the solar system) is 42 km / s. It means that all the speeds of meteors do not exceed parabolic and, therefore, their orbits are closed ellipses.

The kinetic energy of meteor bodies, invading the atmosphere with a very high initial speed, is very large. Mutual collisions of molecules and atoms of meteor and air are intensively ionized gases in a large amount of space around the flying meteor body. The particles, in abundance, eliminated from the meteor body, form a brightly luminous sheath around it with a split vapor. The luminescence of these vapors resembles an electrical arc. The atmosphere at altitudes where meteors appear are very rarely, therefore the process of reunification of the electrons cut off from the atoms continues for quite a long time, while causing a luminaire of an ionized gas, which continues within a few seconds, and sometimes minutes. Such is the nature of the self-losing ionization traces, which can be observed in the sky after many meteors. The spectrum of the luminescence of the trace also consists of the lines of the same elements as the spectrum of the meteor itself, but are already neutral, not ionized. In addition, atmospheric gases also light in the tracks. This is indicated open in 1952-1953. In the spectra of the meteoric trail of the oxygen and nitrogen line.

The meteors spectra show that meteor particles consist either of iron, having a density of more than 8 g / cm 3, or are stone, which should correspond to a density of 2 to 4 g / cm 3. The brightness and spectrum of meteors allow them to evaluate their size and mass. The visible radius of the luminous meteor meteor shell is estimated at about 1-10 cm. However, the radius of the luminous shell, determined by the spout of the luminous particles, is far exceeding the radius of the meteor body itself. Meteoric bodies flying into the atmosphere with a speed of 40-50 km / s and creating the phenomenon of meteors of zero starry, have a radius of about 3 mm, and a mass of about 1 g. The brightness of meteors is proportional to their mass, so that the mass of the meteor of some stellar value in 2, 5 times less than for meteors of the previous value. In addition, the brightness of meteors is proportional to the cube of their speed relative to the Earth.

Entering the Earth's atmosphere with a high initial speed, meteor particles are found at altitudes 80 and more km with a very rarefied gas medium. The air density here is hundreds of millions of times less than that of the earth's surface. Therefore, in this zone, the interaction of the meteor body with the atmospheric medium is expressed in the bombing of the body with individual molecules and atoms. These are molecules and oxygen and nitrogen atoms, since the chemical composition of the atmosphere in the meteor zone is approximately the same as at the sea level. Atoms and molecules of atmospheric gases during elastic collisions are either bounced or penetrated into the crystal lattice of the meteor body. The latter is quickly heated, melted and evaporates. The particle evaporation rate is first insignificant, then increases to a maximum and again decreases by the end of the visible meteor path. The evaporating atoms are flying out of meteor with speeds a few kilometers per second and, having a large energy, are experiencing frequent collisions with air atoms leading to heating and ionization. The declared cloud of evaporated atoms forms a luminous meteor shell. Some of the atoms completely loses the external electrons in collisions, as a result of which a post of ionized gas with a large number of free electrons and positive ions is formed around the meteor trajectory. The amount of electrons in the ionized trail is 10 10 -10 12 per 1 cm path. The initial kinetic energy is spent on heating, glow and ionization in approximately 10 6:10 4: 1.

The deeper the meteor penetrates into the atmosphere, the denser it becomes the hot shell. Like a very fast flying projecture, the meteor forms a head shock wave; This wave accompanies the meteor when it moves in lower layers of the atmosphere, and in the layers below 55 km causes sound phenomena.

Traces remaining after the flight of meteors can be observed both with the help of radar and visually. We particularly successfully observe ionization traces of meteors into light binoculars or telescopes (the so-called cometchers).

Footprints penetrating into lower and dense atmospheric layers, on the contrary, are mainly consisting of dust particles and therefore visible as dark smoky clouds against the blue sky. If such a dust track is illuminated by the rays of the sunstairs or the moon, it is visible like silver stripes against the night sky (Fig. 12). Such traces can be observed by clock until they are destroyed by air currents. Traces of less bright meteors formed at 75 km altitudes and more contain only a very small proportion of dust particles and are visible solely due to the reconnaissance of the atoms of ionized gas. The scope of the ionization trail of the non-equipped eye is an average of 120 seconds on an average of 120 seconds., And for the meteor of the 2nd star value of 0.1 sec., While the radiality duration for the same objects (with geocentric velocity 60 km / s) is equal to 1000 and 0.5 seconds. respectively. The extinction of ionization traces is partially due to the addition of free electrons to oxygen molecules (O 2) contained in the upper layers of the atmosphere.

The most well-studied among small bodies of the solar system are asteroids - small planets. The history of their study includes almost two centuries. Back in 1766, an empirical law was formulated, which determines the average distance of the planet from the Sun, depending on the ordinal number of this planet. In honor of the astronomers that formulated this law, he was called: "Titsius - Bode". a \u003d 0.3 * 2k + 0.4 where the number k \u003d - * for Mercury, k \u003d 0 for Venus, hereinafter k \u003d n - 2 for the Earth and Mars, k \u003d n - 1 for Jupiter, Saturn and Uranus (N - the sequence number of the planet from the sun).

First, astronomers, while maintaining the traditions of the ancients, were assigned to small planets the names of the gods as Greco-Roman and others. By the beginning of the twentieth century, the names of almost all the well-known humanities of the greek, the Greco-Roman, Slavic, Chinese, Scandinavian and even gods of the People of Maya appeared in the sky. Opening continued, the gods began to miss, and then the names of countries, cities, rivers and seas, names and the names of real living or living people began to appear in the sky. Inevitably became the question of streamlining the procedure for this astronomical canonization of names. This question is all the more serious, that, in contrast to the perpetuation of memory on earth (the names of the streets, cities, etc.), the asteroid name cannot be changed. This since its inception (July 25, 1919) is engaged in the International Astronomical Union (MAS).

Large semi-axes of orbits of the main part of asteroids are in the range from 2.06 to 4.09 a. e., and the average value is 2.77 a. e. The average eccentricity of small planets orbits - 0.14, the average slope of the plane of the asteroid orbit to the plane of the Earth's orbit - 9.5 degrees. The speed of the asteroids around the Sun is about 20 km / s, the treatment period (asteroid year) is from 3 to 9 years. The period of own rotation of asteroids (i.e., the duration of the day on the asteroid) is an average of 7 hours.

Not a single asteroid of the main belt, generally speaking, does not pass near the Earth's orbits. However, in 1932 the first asteroid was opened, the orbit of which had a perihelial distance less than the radius of the Earth's orbit. In principle, his orbit allowed the opportunity to rapprocherate an asteroid with the Earth. This asteroid was soon "lost" and again opened in 1973. He received the number 1862 and the name of Apollo. In 1936, an asteroid adonis Asteroid flew at a distance of 2 million km away, and in 1937 - Asteroid Hermes flew at a distance of 750 thousand km from the ground. Hermes has a diameter of almost 1.5 km, and it was opened only 3 months before its maximum rapprochement from the ground. After the prolet, Hermes, astronomers began to be aware of the scientific problem of asteroid danger. By now, about 2000 asteroids, the orbits of which allow them to come closer to Earth. Such asteroids are called asteroids bringing closer to earth.

According to its physical characteristics, asteroids are separated into several groups, inside which objects have similar reflective properties of the surface. Such groups are called taxonomic (taxonometric) classes or types. The table shows 8 major main taxonomic types: C, S, M, E, R, Q, V, and A. Each class of asteroids corresponds to meteorites that have similar optical properties. Therefore, each taxonometric class can be characterized by analogy with the mineralogical composition of the relevant meteorites.

The form and dimensions of these asteroids are determined by radar when they are passing near the ground. Some of them are similar to the main belt asteroids, but their main part is less correct. For example, asteroid Toutatis consists of two, and maybe more in contact with each other bodies.

Based on regular observations and calculations of the orbits of asteroids, you can draw the following conclusion: so far there are no well-known asteroids, about which we can say that in the next hundred years they will come close to Earth. The nearest will be the passage of Asteroid Hator in 2086 at a distance of 883 thousand km.

To date, a number of asteroids passed at distances significantly smaller than the above. They were open during their closest passes. Thus, as long as the main danger is not yet open asteroids.