Meteors in the atmosphere. How is a meteor different from a meteorite? Description, examples of meteors and meteorites Large meteorites discovered in Russia

Since ancient times, there has been a belief that if you make a wish while looking at a shooting star, it will definitely come true. Have you ever thought about the nature of the phenomenon of falling stars? In this lesson we will discover what star showers, meteorites and meteors are.

Theme: Universe

Lesson: Meteors and meteorites

Phenomena observed in the form of short-term flashes that occur during the combustion of small meteoric objects (for example, fragments of comets or asteroids) in the earth's atmosphere. Meteors streak across the sky, sometimes leaving behind a narrow glowing trail for a few seconds before disappearing. In everyday life they are often called shooting stars. For a long time, meteors were considered a common atmospheric phenomenon such as lightning. Only at the very end of the 18th century, thanks to observations of the same meteors from different points, their altitudes and speeds were first determined. It turned out that meteors are cosmic bodies that enter the Earth’s atmosphere from the outside at speeds from 11 km/sec to 72 km/sec, and burn up in it at an altitude of about 80 km. Astronomers began to seriously study meteors only in the 20th century.

The distribution across the sky and the frequency of occurrence of meteors are often not uniform. So-called meteor showers occur systematically, the meteors of which appear in approximately the same part of the sky over a certain period of time (usually several nights). Such streams are given the names of constellations. For example, the meteor shower that occurs annually from approximately July 20 to August 20 is called the Perseids. The Lyrid (mid-April) and Leonid (mid-November) meteor showers take their names from the constellations Lyra and Leo, respectively. In different years, meteorite showers exhibit different activity. The change in the activity of meteor showers is explained by the uneven distribution of meteor particles in the streams along the elliptical orbit intersecting the earth's.

Rice. 2. Perseid meteor shower ()

Meteors that do not belong to showers are called sporadic. On average, about 108 meteors brighter than 5th magnitude flare up in the Earth's atmosphere during the day. Bright meteors occur less frequently, weak ones more often. Fireballs(very bright meteors) can be visible even during the day. Sometimes fireballs are accompanied by meteorite falls. Often the appearance of a fireball is accompanied by a fairly powerful shock wave, sound phenomena, and the formation of a smoke tail. The origin and physical structure of the large bodies observed as fireballs are likely to be quite different compared to the particles that cause meteoric phenomena.

It is necessary to distinguish between meteors and meteorites. A meteor is not the object itself (that is, the meteor body), but the phenomenon, that is, its luminous trail. This phenomenon will be called a meteor, regardless of whether the meteoroid flies away from the atmosphere into outer space, burns up in it, or falls to Earth in the form of a meteorite.

Physical meteorology is the science that studies the passage of a meteorite through the layers of the atmosphere.

Meteor astronomy is the science that studies the origin and evolution of meteorites

Meteor geophysics is the science that studies the effects of meteors on the Earth's atmosphere.

- a body of cosmic origin that fell onto the surface of a large celestial object.

According to their chemical composition and structure, meteorites are divided into three large groups: stone, or aerolites, iron-stone, or siderolites, and iron - siderites. The opinion of most researchers agrees that stone meteorites predominate in outer space (80-90% of the total), although more iron meteorites have been collected than stone ones. The relative abundance of different types of meteorites is difficult to determine, since iron meteorites are easier to find than stone meteorites. In addition, stony meteorites are usually destroyed when passing through the atmosphere. When a meteorite enters the dense layers of the atmosphere, its surface becomes so hot that it begins to melt and evaporate. Jets of air blow away large drops of molten matter from iron meteorites, while traces of this blowing remain and can be observed in the form of characteristic notches. Rocky meteorites often break up, scattering a shower of fragments of various sizes onto the Earth's surface. Iron meteorites are more durable, but they sometimes break into separate pieces. One of the largest iron meteorites, which fell on February 12, 1947 in the Sikhote-Alin region, was discovered in the form of a large number of individual fragments, the total weight of which is 23 tons, and, of course, not all the fragments were found. The largest known meteorite, Goba (in South-West Africa), is a block weighing 60 tons.

Rice. 3. Goba - the largest meteorite found ()

Large meteorites burrow to a considerable depth when they hit the Earth. In this case, in the Earth's atmosphere at a certain altitude, the cosmic velocity of a meteorite is usually extinguished, after which, having slowed down, it falls according to the laws of free fall. What will happen when a large meteorite, for example, weighing 105-108 tons, collides with the Earth? Such a gigantic object would pass through the atmosphere almost unhindered, and when it fell, a powerful explosion would occur with the formation of a funnel (crater). If such catastrophic events ever occurred, we should find meteorite craters on the surface of the Earth. Such craters really exist. Thus, the funnel of the largest, Arizona, crater has a diameter of 1200 m and a depth of about 200 m. According to a rough estimate, its age is about 5 thousand years. Not long ago, several more ancient and destroyed meteorite craters were discovered.

Rice. 4. Arizona meteorite crater ()

Shock crater(meteor crater) - a depression on the surface of a cosmic body, the result of the fall of another smaller body.

Most often, a meteor shower of high intensity (with a zenith hour number of up to a thousand meteors per hour) is called a star or meteor shower.

Rice. 5. Star rain ()

1. Melchakov L.F., Skatnik M.N. Natural history: textbook. for 3.5 grades avg. school - 8th ed. - M.: Education, 1992. - 240 pp.: ill.

2. Bakhchieva O.A., Klyuchnikova N.M., Pyatunina S.K., et al. Natural history 5. - M.: Educational literature.

3. Eskov K.Yu. and others. Natural history 5 / Ed. Vakhrusheva A.A. - M.: Balass

1. Melchakov L.F., Skatnik M.N. Natural history: textbook. for 3.5 grades avg. school - 8th ed. - M.: Education, 1992. - p. 165, tasks and question. 3.

2. How are meteor showers named?

3. How does a meteorite differ from a meteor?

4. * Imagine that you have discovered a meteorite and want to write an article about it for a magazine. What would this article look like?

On a clear dark night, especially in mid-August, November and December, you can see “shooting stars” streaking the sky - these are meteors, an interesting natural phenomenon known to man since time immemorial.

Meteors, especially in recent years, have attracted close attention from astronomical science. They have already told a lot about our solar system and about the Earth itself, in particular about the earth’s atmosphere.

Moreover, meteors, figuratively speaking, repaid the debt, reimbursed the funds spent on their study, making a contribution to solving some practical problems of science and technology.

Meteor research is actively developing in a number of countries, and our short story is dedicated to some of this research. We will start it by clarifying the terms.

An object moving in interplanetary space and having dimensions, as they say, “larger than molecular, but smaller than asteroidal,” is called a meteoroid, or meteoroid. Invading the earth's atmosphere, a meteoroid (meteor body) heats up, glows brightly and ceases to exist, turning into dust and vapor.

The light phenomenon caused by the combustion of a meteoroid is called a meteor. If a meteoroid has a relatively large mass and if its speed is relatively low, then sometimes part of the meteoroid body, not having time to completely evaporate in the atmosphere, falls to the surface of the Earth.

This fallen part is called a meteorite. Extremely bright meteors that look like a fireball with a tail or a burning brand are called fireballs. Bright fireballs are sometimes visible even during the day.

Why are meteors studied?

Meteors have been observed and studied for centuries, but only in the last three or four decades have the nature, physical properties, orbital characteristics and origin of those cosmic bodies that are sources of meteorites become clearly understood. Researchers' interest in meteor phenomena is associated with several groups of scientific problems.

First of all, studying the trajectory of meteors, the processes of glow and ionization of meteoroid matter is important for elucidating their physical nature, and they, meteoroid bodies, after all, are “test portions” of matter that arrived to the Earth from distant regions of the Solar System.

Further, the study of a number of physical phenomena accompanying the flight of a meteoric body provides rich material for studying the physical and dynamic processes occurring in the so-called meteor zone of our atmosphere, that is, at altitudes of 60-120 km. Meteors are mainly observed here.

Moreover, for these layers of the atmosphere, meteors, perhaps, remain the most effective “research tool,” even against the backdrop of the current scope of research using spacecraft.

Direct methods for studying the upper layers of the Earth's atmosphere with the help of artificial Earth satellites and high-altitude rockets began to be widely used many years ago, since the International Geophysical Year.

However, artificial satellites provide information about the atmosphere at altitudes of more than 130 km; at lower altitudes, satellites simply burn up in dense layers of the atmosphere. As for rocket measurements, they are carried out only over fixed points on the globe and are of a short-term nature.

Meteor bodies are full-fledged inhabitants of the solar system; they revolve in geocentric orbits, usually elliptical in shape.

By assessing how the total number of meteoroids is distributed into groups with different masses, velocities, and directions, it is possible not only to study the entire complex of small bodies of the Solar System, but also to create a basis for constructing a theory of the origin and evolution of meteoric matter.

Recently, interest in meteors has also increased due to the intensive study of near-Earth space. An important practical task has become the assessment of the so-called meteor hazard on various space routes.

This, of course, is only a particular question; space and meteor research have many common points, and the study of meteor particles has become firmly established in space programs. For example, with the help of satellites, space probes and geophysical rockets, valuable information has been obtained about the smallest meteoroids moving in interplanetary space.

Here is just one figure: sensors installed on spacecraft make it possible to record meteoroid impacts, the sizes of which are measured in thousandths of a millimeter (!).

How meteors are observed

On a clear moonless night, meteors up to 5th and even 6th magnitude can be seen - they have the same brightness as the faintest stars visible to the naked eye. But mostly, slightly brighter meteors, brighter than 4th magnitude, are visible to the naked eye; On average, about 10 such meteors can be seen within an hour.

In total, there are about 90 million meteors in the Earth’s atmosphere per day, which could be seen at night. The total number of meteoroids of various sizes invading the earth's atmosphere per day amounts to hundreds of billions.

In meteor astronomy, it was agreed to divide meteors into two types. Meteors that are observed every night and move in a variety of directions are called random, or sporadic. Another type is periodic, or streaming, meteors; they appear at the same time of year and from a certain small area of ​​​​the starry sky - the radiant. This word - radiant - in this case means “radiating area”.

Meteor bodies that give rise to sporadic meteors move in space independently of each other along a wide variety of orbits, and periodic ones move along almost parallel paths, which precisely emanate from the radiant.

Meteor showers are named after the constellations in which their radiants are located. For example, the Leonids are a meteor shower with a radiant in the constellation Leo, the Perseids - in the constellation Perseus, the Orionids - in the constellation Orion, and so on.

Knowing the exact position of the radiant, the moment and speed of the meteor's flight, it is possible to calculate the elements of the meteoroid's orbit, that is, to find out the nature of its movement in interplanetary space.

Visual observations made it possible to obtain important information about daily and seasonal changes in the total number of meteors and the distribution of radiants across the celestial sphere. But mainly photographic, radar, and, in recent years, electro-optical and television observation methods are used to study meteors.

Systematic photographic recording of meteors began about forty years ago; so-called meteor patrols are used for this purpose. A meteor patrol is a system of several photographic units, and each unit usually consists of 4-6 wide-angle photographic cameras, installed so that they all together cover the largest possible area of ​​​​the sky.

Observing a meteor from two points 30-50 km apart from each other, using photographs against the background of stars it is easy to determine its height, trajectory in the atmosphere and radiant.

If a shutter, that is, a rotating shutter, is placed in front of the cameras of one of the patrol units, then the speed of the meteoroid can be determined - instead of a continuous trace on the photographic film, you will get a dotted line, and the length of the strokes will be precisely proportional to the speed of the meteoroid.

If prisms or diffraction gratings are placed in front of the camera lenses of another unit, then the spectrum of the meteor appears on the plate, just as the spectrum of a sunbeam appears on a white wall after passing through the prism. And from the spectra of the meteor, one can determine the chemical composition of the meteoroid.

One of the important advantages of radar methods is the ability to observe meteors in any weather and around the clock. In addition, radar makes it possible to register very faint meteors up to 12-15 stellar magnitude, generated by meteoroids with a mass of millionths of a gram or even less.

The radar “detects” not the meteor body itself, but its trace: when moving in the atmosphere, the evaporated atoms of the meteor body collide with air molecules, are excited and turn into ions, that is, mobile charged particles.

Ionized meteor trails are formed, having a length of several tens of kilometers and initial radii of the order of a meter; These are a kind of hanging (of course, not for long!) atmospheric conductors, or more precisely semiconductors - they can count from 106 to 1016 free electrons or ions for every centimeter of trace length.

This concentration of free charges is quite enough for radio waves in the meter range to be reflected from them, as from a conducting body. Due to diffusion and other phenomena, the ionized trail quickly expands, its electron concentration drops, and under the influence of winds in the upper atmosphere the trail dissipates.

This allows radar to be used to study the speed and direction of air currents, for example, to study the global circulation of the upper atmosphere.

In recent years, observations of very bright fireballs, which are sometimes accompanied by meteorite falls, have become increasingly active. Several countries have established fireball observation networks with all-sky cameras.

They actually monitor the entire sky, but only record very bright meteors. Such networks include 15-20 points located at a distance of 150-200 kilometers; they cover large areas, since the invasion of the earth’s atmosphere by a large meteoroid is a relatively rare phenomenon.

And here’s what’s interesting: out of several hundred bright fireballs photographed, only three were accompanied by a meteorite fall, although the speeds of large meteoroids were not very high. This means that the above-ground explosion of the Tunguska meteorite of 1908 is a typical phenomenon.

Structure and chemical composition of meteoroids

The invasion of a meteoroid into the earth's atmosphere is accompanied by complex processes of its destruction - melting, evaporation, sputtering and crushing. Atoms of meteoric matter, when colliding with air molecules, are ionized and excited: the glow of a meteor is mainly associated with the radiation of excited atoms and ions; they move at the speeds of the meteoric body itself and have a kinetic energy of several tens to hundreds of electron-volts.

Photographic observations of meteors using the instantaneous exposure method (about 0.0005 sec.), developed and implemented for the first time in the world in Dushanbe and Odessa, clearly showed various types of fragmentation of meteoric bodies in the earth’s atmosphere.

Such fragmentation can be explained both by the complex nature of the processes of destruction of meteoroids in the atmosphere, and by the loose structure of meteoroids and their low density. The density of meteoroids of cometary origin is especially low.

The spectra of meteors mainly show bright emission lines. Among them, lines of neutral atoms of iron, sodium, manganese, calcium, chromium, nitrogen, oxygen, aluminum and silicon, as well as lines of ionized atoms of magnesium, silicon, calcium and iron were found. Like meteorites, meteoroids can be divided into two large groups - iron and stone, and there are significantly more stone meteoroids than iron ones.

Meteor material in interplanetary space

Analysis of the orbits of sporadic meteoroids shows that meteoric matter is concentrated mainly in the ecliptic plane (the plane in which the orbits of the planets lie) and moves around the Sun in the same direction as the planets themselves. This is an important conclusion; it proves the common origin of all bodies in the Solar System, including such small ones as meteoroids.

The observed speed of meteoroids relative to the Earth lies in the range of 11-72 km/sec. But the speed of the Earth’s movement in its orbit is 30 km/sec, which means that the speed of meteoroids relative to the Sun does not exceed 42 km/sec. That is, it is less than the parabolic speed that is necessary to exit the solar system.

Hence the conclusion - meteoroids do not come to us from interstellar space, they belong to the Solar System and move around the Sun in closed elliptical orbits. Based on photographic and radar observations, the orbits of several tens of thousands of meteoroids have already been determined.

Along with the gravitational attraction of the Sun and planets, the movement of meteoroids, especially small ones, is significantly influenced by the forces caused by the influence of electromagnetic and corpuscular radiation from the Sun.

So, in particular, under the influence of light pressure, the smallest meteoric particles less than 0.001 mm in size are pushed out of the Solar System. In addition, the movement of small particles is significantly influenced by the braking effect of radiation pressure (the Poynting-Robertson effect), and because of this, the orbits of the particles are gradually “compressed”, they are getting closer and closer to the Sun.

The lifetime of meteoroids in the inner regions of the Solar System is short, and, therefore, the reserves of meteoric matter must somehow be constantly replenished.

Three main sources of such replenishment can be identified:

1) decay of cometary nuclei;

2) fragmentation of asteroids (remember, these are small planets moving mainly between the orbits of Mars and Jupiter) as a result of their mutual collisions;

3) an influx of very small meteoroids from the distant environs of the Solar System, where, probably, there are remnants of the material from which the Solar System was formed.

We have debunked shooting stars as true stars - these greatest celestial bodies - and recognized them as only insignificant pebbles. These pebbles, while they are rushing outside the earth's atmosphere, are insignificant, but still celestial bodies, and the study of them as such has taken us into the depths of interplanetary space and forced us to turn to other and much more significant celestial bodies - comets. But, having entered the Earth’s atmosphere and glowing in it for a short time, both the meteor and the meteorite cease to be essentially celestial bodies. Their flight in the air is accompanied by special interesting phenomena, and a small meteor pebble ceases to be such, which is why some scientists propose calling all such pebbles meteor bodies, and by a meteor we mean only the very phenomenon of glow during its flight in the atmosphere. It seems to us that there is no particular need for this and this causes its own inconveniences, but let us pay some attention to why and how meteors, once in the atmosphere, become visible, and what the study of these phenomena gives us for understanding our own planet...

A star silently rolling across the sky, a fragment of a distant comet and gun salvoes, shelling and bombing of peaceful rear cities, what, it seems, could be common between them?!

1918... The German armies are rushing towards Paris, but they are far away, it is definitely known that the enemy is no closer than 120 km from the city, there is no reason to panic. And suddenly... large shells begin to explode in the vicinity of Paris. What to think... Where is the enemy?

It turned out that the Germans had created ultra-long-range guns that could fire at a distance of 120 km. These guns fired projectiles weighing 120 kg from a 37 m long barrel with an initial speed of 1700 m/s at an angle of 55° to the horizontal. This was the main secret of ultra-long range. Quickly cutting through the lower dense layers of air, the projectile climbed into the upper rarefied layers of the earth's atmosphere, far into the stratosphere, to a height of 40 km. There, the thin air did little to slow down its movement, and instead of several tens of kilometers, the projectile flew a hundred kilometers. It must be said that the Germans’ shooting was not very accurate; they were counting more on creating panic.

A certain amount of inaccuracy in their shooting was due to the inability to accurately calculate the flight conditions of a projectile at high altitude. Neither the density, nor the composition, nor the movement of air at this altitude were then known; the atmosphere at these altitudes has not yet been studied. Indeed, even stratospheric balloons, which subsequently lifted people with scientific instruments, reached a height of only about 22 km, and balloons with recording instruments without people rose to 30 km. Missiles rising to altitudes of more than 100 km began to be launched only after the Second World War.

The higher strata of the air could formerly be known only by studying the phenomena occurring there, and the meteors which daily pierce them still furnish one of the best indirect methods of the kind. Only quite recently have scientists received such a powerful means of comprehensive study of the upper layers of the atmosphere as artificial Earth satellites. That is why intensive study of meteors was an important point in the program of the International Geophysical Year (1957-1958).

Meteors are unwitting scouts of the stratosphere, and our task is to learn how to interrogate them. This is what the results of such a survey, begun only about forty years ago, lead to.

Meteor bodies enter the atmosphere at a speed approximately one hundred times greater than the speed of a rifle bullet at the beginning of its path. As is known, kinetic energy, i.e. the energy of motion of a body, is equal to half the product of the square of its speed and its mass. All this meteor energy is used to emit heat and light, to fragment the body into molecules, to break down the molecules of the body and air into atoms and to ionize these atoms.

Molecules and atoms of a solid body, including a meteor, are often arranged in a certain order, forming a so-called crystal lattice. With monstrous speed, the meteor crashes into the air, and the molecules that make up the air are forcefully squeezed into the molecular lattice of the meteoric body. The further a meteor flies into the earth's atmosphere, the denser the air there is and the more and more the molecular lattice of the meteoric body is subjected to fierce bombardment by air molecules.

The frontal part of the meteor eventually receives a shower of impacts in which air molecules pierce the meteor, penetrating inside it, like a projectile into a reinforced concrete pillbox. This “shelling” of the front surface disrupts the connections between the molecules and atoms of the body, breaks the crystal lattices and pulls out from them individual molecules of the meteor’s substance, which accumulate in disorder on its frontal surface. Some molecules are broken down into the atoms from which they are composed. Some atoms even lose their constituent electrons from impacts, i.e., they become ionized, acquiring an electrical charge. The split-off electrons, from time to time sliding too close to the ions, are captured by them in “vacant places” and at the same time, in accordance with the laws of physics, emit light. Each atom emits its own wavelengths, which is why the spectrum of the meteor is a bright line spectrum, characteristic of the glow of rarefied gases.

The deeper into the atmosphere, the faster the meteor disintegrates and the stronger its glow. At an altitude below 130 km above the Earth, it is already enough to make the meteor visible to us.

Air molecules also suffer during impacts, but they are stronger than the molecules and atoms of a meteor and are less likely to be ionized; in addition, they are not so highly concentrated and therefore give such a weak glow that the lines of gases that make up the atmosphere (mainly oxygen and nitrogen) are in the spectrum we don't notice the meteor.

Lower in the atmosphere, the air in front of the frontal surface of the meteor forms a “cap” consisting of compressed gases into which the meteor turns, and partly from the gases of the air it compresses in front of it. Jets of compressed and hot gas flow around the meteor body from the sides, tearing off new particles from it and accelerating the destruction of the pebble.

Larger meteoroids penetrate deep into the atmosphere without having time to completely turn into gas. For them, braking leads to a loss of their cosmic velocity at an altitude of 20-25 km. From this “delay point,” as it is called, they fall almost vertically, like bombs from a dive plane.

In the low layers of the atmosphere, an abundance of solid particles torn from the sides of the meteor body and left behind forms a “smoky” black or white dust trail behind it, often visible during the flight of bright fireballs. When such a body is large enough, air rushes into the rarefaction formed behind it. This, as well as the compression and rarefaction of air in the path of a large meteoroid, causes sound waves. Therefore, the flight of bright fireballs is accompanied by sounds that sometimes resemble gunshots and thunderclaps.

Both the brightness and color of meteors and fireballs are created not by an incandescent solid surface, which is negligible, but by particles of matter turned into gas. Therefore, their color depends not so much on temperature, but on which of the light lines in its visible spectrum are the brightest. The latter depends on the chemical composition of the body and on the conditions of its luminescence, determined by its speed. In general, a reddish color accompanies a lower speed.

This is, in brief, the picture of the glow of meteoroids in the atmosphere that modern science paints.

Let us dwell on some details of these phenomena, studied quite recently and related to the study of the stratosphere. For example, studies of meteor deceleration shed light on changes in air density with altitude. The greater the air density, the stronger the braking, of course, but braking depends both on the speed of movement and on the shape of the body, which is why they strive to give airplanes, cars and even locomotives a “streamlined shape.” The “streamlined” body is devoid of sharp corners and is designed so that when moving quickly, air flows around it, encountering as little interference and resistance as possible, and therefore slows down the movement less.

Artillery shells experience enormous air resistance in flight. Meteor bodies fly in the air at a speed tens of times higher than the speed of the projectile, and for them the air resistance is even greater. Based on a photograph of a meteor taken once in Moscow by amateur astronomers, members of the Astronomical and Geodetic Society, with a camera with a sector rotating in front of the lens, for one meteor they found a deceleration (which is often called negative acceleration) of about 40 km/s². This is 400 times greater than the acceleration of free falling bodies under the influence of gravity! And this is at an altitude of 40 km above the Earth, where the air is so rarefied that a person there would immediately die from suffocation.

In order for sound to be heard, the air must have a certain density. There are no sounds in airless space, and just as a bell in a vacuum under the hood of an air pump at a physics lecture tries in vain, so in airless interplanetary space world catastrophes occur silently. A grandiose explosion of a “new star” or collisions of stars (albeit almost incredible) occur so silently that, being close to them at the moment of the catastrophe, we would not even turn around if it happened “behind us”.

The nature of the sounds during the flight of fireballs tells us a lot about the density of the upper layers of the atmosphere.

A good opportunity to study air currents in high layers of the atmosphere is provided by the traces remaining in the sky after the flight of bright meteors and fireballs; 20-80 km - this is their height above our heads.

How long dust trails are visible depends on lighting conditions and the amount of material converted into fine airborne dust. Air currents also play a role here, carrying dust particles to the sides and “sweeping up” the track of the car. In exceptional cases, the car's trail is visible for 5-6 hours.

The silvery trails visible at night after the passage of fast and bright meteors are of a different nature - they are gaseous and always lie above 80 km. At the enormous speed of colliding molecules along the path of the meteor, strong ionization of air molecules occurs, which is also helped by the ultraviolet radiation of the meteor. In the cylinder of ionized air formed behind the meteor, the reunification of ions with electrons slowly occurs, slowly because with the high rarefaction of the air at such a height, the electrified particles are far from each other and travel a long way before reuniting again. The process of their reunification, as always, is accompanied by the emission of spectrum lines. At the same time, the ionized molecules fly apart, and the width of the trace increases. This, of course, weakens the brightness of the trace, but other traces (usually visible only for a few seconds) remain in the sky among the stars, sometimes even for an hour.

The continuous ionization of the air by meteors contributes to the maintenance of ionized layers at altitudes from 80 to 300-350 km above the Earth. The main reason for their occurrence is the ionization of air by solar light (ultraviolet) and corpuscular rays (streams of electrified particles).

Perhaps not everyone knows that it is precisely these layers that we owe to the fact that on short waves it is possible to communicate with shortwave amateurs living in the Malay Archipelago or in South Africa. Radio signals emitted by the transmitter and incident on these layers at a certain angle, due to its electrical conductivity, are reflected as if from a mirror. They do not go into outer space, but, reflected downwards, are received almost unattenuated somewhere very far from the transmitting radio station.

This phenomenon of reflection of radio waves is also related to the length of the radio wave. It is possible to study the density of ions in the electrically conductive layer of the atmosphere by changing the wavelength and determining when the radio transmission stops, that is, when the radio waves escape from the earth's atmosphere rather than being reflected. Other radio observations monitor the height of the layers, which fluctuate somewhat.

As might be expected, it was found that changes in the number of meteors entering the atmosphere, and even the appearance of individual bright fireballs, change the strength of short-wave radio reception, causing rapid, short-term changes in the electrical conductivity of the air due to its ionization at altitudes of 50-130 km. Large disturbances in the strength of radio reception of distant stations were, for example, noted at the Slutsk Observatory near Leningrad during the Draconid meteor shower on October 9, 1933.

This is how radio communications react in an unexpected way to the appearance of the mortal remains of comets, luminaries, seemingly so indifferent to everyday affairs on our Earth!

About a hundred years ago, the famous Moscow astronomer V.K. Tserasky accidentally noticed in the summer unusual noctilucent clouds glowing in the night sky in its northern part. These could not be ordinary clouds floating no higher than 8, or at most 12 km above the Earth. If it were them, then the Sun, located under the horizon, could not reach them with its rays and make them glow so brightly. These must have been unusually high clouds. And indeed, a comparison of sketches of their position against the background of stars, made simultaneously from two different places (V.K. Tserasky and A.A. Belopolsky), allowed the first of them to prove for the first time that these clouds walk at an altitude of 80-85 km. Since then, they have been observed more than once, always in the summer and in the northern part of the sky, near the horizon, since even at such a high altitude and only under these conditions the sun’s rays can illuminate them from under the horizon.

These nightly “luminous” or “silver” clouds, as they are called, always stubbornly remain at an altitude of 82 km. Perhaps these clouds, lying near the lower limit of meteor extinction, are formed by ice crystals frozen onto dust particles.

That there is dust in the air at an altitude of 80 km, where it would seem to be so “clean” (remember the cleanliness of the air in the mountains!), this still seems to go without saying. But what would you think if someone told you about the metallic atmosphere above our heads!

We rightly rejected the naive ideas of antiquity about the “firmament”, about the “crystal heavens” above our heads, and suddenly we recognize... almost a metal sky!

In fact, in 1938, a spectroscope in the hands of the French astrophysicists Cabanne, Dufay and Gozi showed with deadly composure that the spectrum of the night sky constantly contains the famous yellow sodium line and calcium lines. In addition to these metals, scientists hope to find aluminum and even iron in the atmosphere! (By the way, to get the light spectrum of the night sky, which already appears almost black, i.e., emitting almost no light, one has to make many hours of exposure.) Metals found in the atmosphere belong to an altitude of 130 km above the Earth and, Of course, they do not form any solid dome. Individual atoms of the named metals are found in very few units among the numerous molecules of extremely rarefied air at this altitude. Apparently, metal atoms are scattered in the atmosphere during the evaporation of meteors and glow when they collide with other particles. In fact, one way or another, the products of meteor evaporation, i.e., mainly atoms of heavy elements, should not only remain, but also accumulate in the atmosphere. Whether they will glow there or not is a separate question, but there is no reason that, dispersing at an altitude of about a hundred kilometers, they could immediately fall to the ground.

So, meteoric matter is everywhere, it lies under our feet, it continuously travels in space, it hangs above our heads.

The study of meteor phenomena has provided much valuable information for understanding the stratosphere. Not all of these conclusions, such as the first conclusions of foreign scientists Lindemann and Dobson, are indisputable in the very young science of the movement of meteors in the atmosphere, but they still illustrate the possibilities that open up for us here. And these are the conclusions. Based on their theory of the glow of meteoric bodies in the atmosphere, which considers the interaction with the air of a flying meteoric body, the mentioned authors in 1923 explained the features in the distribution of meteor extinction points along the height and concluded that at an altitude of about 60 km the air is very heated. They calculated the temperature there, and it turned out to be +30°, and later calculations even led to a temperature of 110°. (We will not say that at this altitude the temperature turned out to be above the boiling point of water, because at those low air pressures that occur in the stratosphere, the boiling point of water is much lower than 100°C.)

This discovery was a surprise, because direct measurements of temperature up to an altitude of 30 km showed at first a rapid drop with altitude, and from 11 km (the lower boundary of the stratosphere) a layer began with an almost constant temperature of 50° below zero, regardless of the time of year and climatic zone terrain. Or rather, the stratosphere even behaves “topsy-turvy”: in winter, even in polar countries, its temperature is about -45°, and in summer and in the tropics about -90°. The troposphere, or the lower layer of the earth's atmosphere, is characterized by a drop in temperature with height and extends higher above the equator (up to 15-16 km) than at the Earth's poles (9-10 km). This upper boundary - the end of the temperature change - determines the beginning of the stratosphere, to a certain extent explaining the unexpected distribution of stratosphere temperature across climate zones, since the temperature of the stratosphere is equal to the temperature of the upper boundary of the troposphere. Seasonal and unexpected changes in its temperature are also associated with seasonal changes in the height of the troposphere boundary, since the air is heated primarily from below, by the ground, and in winter the ground is less heated and warms the atmosphere to a lower altitude.

The study of meteors unexpectedly discovered the existence of a new increase in temperature with height, as they say, an upper temperature inversion in the stratosphere. A stratonaut who ascends into the stratosphere in a fur suit, if he can rise above 40 km, will probably find it more difficult to protect himself from the heat that will replace the 50-degree frost that prevails below.

The existence of an upper temperature inversion is confirmed by studying the deceleration of meteors from photographs with a rotating sector. This inhibition decreases in the very region where the temperature is expected to increase, as it should. Recently, a temperature of +50°C at an altitude of 60 km was also found by direct measurements using instruments installed on rockets launched into the stratosphere.

From the point of view of studying the stratosphere, it is also interesting that the speed of spreading of gaseous luminous meteor trails is related to the pressure and temperature of the surrounding layers of air and makes it possible to estimate their magnitude.

Previously, the stratosphere was considered a region of undisturbed peace, frozen in the stillness of the air ocean, attributing all winds and movements of air masses to the troposphere. Therefore, it was a complete surprise when Soviet scientists discovered I.S. Astapovich, V.V. Fedynsky and other air currents at an altitude of 80 km above the Earth, with speeds reaching up to 120 m/s, carrying meteor trails mainly to the east, but sometimes in the other direction; There are even vertical currents.

The study of meteors in connection with the properties of the stratosphere has just begun, and the data presented are only the first of its gifts, which can convince even the most skeptical people of the benefits of this branch of astronomy.

METEORS AND METEORITES

A meteor is a cosmic particle that enters the earth's atmosphere at high speed and completely burns up, leaving behind a bright luminous trajectory, colloquially called a shooting star. The duration of this phenomenon and the color of the trajectory can vary, although most meteors appear and disappear in a fraction of a second.

A meteorite is a larger fragment of cosmic matter that does not completely burn up in the atmosphere and falls to Earth. There are many such fragments orbiting the Sun, varying in size from several kilometers to less than 1 mm. Some of them are particles from comets that have undergone disintegration or passed through the inner solar system.

Single meteors that enter the earth's atmosphere by chance are called sporadic meteors. At certain times, when the Earth crosses the orbit of a comet or comet remnant, meteor showers occur.

When viewed from Earth, the paths of meteors during a meteor shower appear to originate from a specific point in the constellation, called the meteor shower radiant. This phenomenon occurs because the particles are in the same orbit with the comet of which they are fragments. They enter the Earth's atmosphere from a certain direction, corresponding to the direction of the orbit when observed from Earth. The most notable meteor showers include the Leonids (in November) and the Perseids (in late July). Every year, meteor showers are especially intense when particles gather in a dense swarm in orbit and the Earth passes through the swarm.

Meteorites are typically iron, stony, or stony-iron. Most likely, they are formed as a result of collisions between larger bodies in the asteroid belt, when individual rock fragments are scattered into orbits that intersect the orbit of the Earth. The largest meteorite discovered, weighing 60 tons, fell in South-West Africa. It is believed that the fall of a very large meteorite marked the end of the age of dinosaurs many millions of years ago. In 1969, a meteorite disintegrated in the skies over Mexico, scattering thousands of fragments over a wide area. Subsequent analysis of these fragments led to the theory that the meteorite was formed by a nearby supernova explosion several billion years ago.

See also the articles "Earth's Atmosphere", "Comets", "Supernova".

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What are meteors made of? Perhaps you have seen a picture where one of the stars suddenly fell from the sky and rushed to the ground. For a long time, these shooting stars remained a mystery to people. In fact, these objects have nothing to do with real stars.

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How are meteors different from meteorites? Meteors, or “shooting stars,” are short-term light phenomena in the earth’s atmosphere, flashes generated by particles of cosmic matter (so-called meteor bodies), which travel at speeds of tens of kilometers per

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What are Meteora? Meteora are famous Greek monasteries, unique primarily in that they are all located on the tops of cliffs reaching a height of 600 meters above sea level. They were built in the 10th century, six are still in use. The rocks on which

Description

Meteors should be distinguished from meteorites and meteoroids. A meteor is not an object (that is, a meteoroid), but a phenomenon, that is, a luminous trace of a meteoroid. And this phenomenon is called a meteor, regardless of whether the meteoroid flies from the atmosphere back into outer space, burns up in it due to friction, or falls to Earth as a meteorite.

The distinctive characteristics of a meteor, in addition to mass and size, are its speed, ignition height, track length (visible path), brightness and chemical composition (affects the color of combustion). So, provided that a meteor reaches 1 magnitude at a speed of entry into the Earth’s atmosphere of 40 km/s, lights up at an altitude of 100 km, and goes out at an altitude of 80 km, with a path length of 60 km and a distance to the observer of 150 km, then The flight duration will be 1.5 seconds, and the average size will be 0.6 mm with a mass of 6 mg.

Meteors are often grouped into meteor showers - constant masses of meteors that appear at a certain time of year, in a certain side of the sky. Widely known meteor showers are the Leonids, Quadrantids and Perseids. All meteor showers are generated by comets as a result of destruction during the melting process while passing through the inner solar system.

During visual observations of meteor showers, meteors appear to originate from a single point in the sky - the radiant of the meteor shower. This is explained by the similar origin and relatively close location of cosmic dust in outer space, which is the source of meteor showers.

The meteor trail usually disappears in a matter of seconds, but can sometimes remain for minutes and move with the wind at the altitude of the meteor. Visual and photographic observations of a meteor from one point on the earth's surface determine, in particular, the equatorial coordinates of the starting and ending points of the meteor trail, and the position of the radiant from observations of several meteors. Observations of the same meteor from two points - the so-called corresponding observations - determine the flight altitude of the meteor, the distance to it, and for meteors with a stable trail - the speed and direction of movement of the trail, and even build a three-dimensional model of its movement.

In addition to visual and photographic methods for studying meteors, electron-optical, spectrometric, and especially radar methods, based on the property of a meteor trail to scatter radio waves, have developed in the last half century. Radio meteor sounding and the study of the movement of meteor trails makes it possible to obtain important information about the state and dynamics of the atmosphere at altitudes of about 100 km. It is possible to create meteor radio communication channels. Main installations for meteor research: photographic meteor patrols, meteor radar stations. Of the major international programs in the field of meteor research, the one carried out in the 1980s deserves attention. GLOBMET program.

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17F45 No. 101 Customer ... Wikipedia

- (Greek). Any air phenomenon, for example, thunder, lightning, rainbow, rain. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. METEOR is an air phenomenon, in general any change in the state of the atmosphere and anything that happens in ... Dictionary of foreign words of the Russian language

meteor- a, m. météore m., German. Meteor n. lat. meteoron gr. meteoros located at a height, in the air. 1. An air phenomenon, in general any change in the state of the atmosphere and any phenomenon occurring in it. Pavlenkov 1911. trans. He… … Historical Dictionary of Gallicisms of the Russian Language

1) meteorological space system, including artificial Earth satellites Cosmos and Meteor, points for receiving, processing and disseminating meteorological information, monitoring and control services for on-board systems of artificial Earth satellites.… … Big Encyclopedic Dictionary

METEOR, meteora, husband. (Greek: meteoros). 1. Any atmospheric phenomenon, eg. rain, snow, rainbow, lightning, mirage (meteor). 2. Same as meteorite (astro.). || trans. In comparisons about something that suddenly appears, produces an effect and quickly... ... Ushakov's Explanatory Dictionary

- (shooting star), a thin streak of light that appears briefly in the night sky as a result of the intrusion into the upper atmosphere of a meteoroid (a solid particle, usually the size of a speck of dust) traveling at high speed. Meteors appear on... ... Scientific and technical encyclopedic dictionary

METEOR, huh, husband. 1. The flash of a small celestial body flying into the upper atmosphere from space. Flashed like a m. (appeared suddenly and disappeared). 2. Fast passenger hydrofoil ship, rocket (in 3 digits). | adj. meteor, oh, oh... ... Ozhegov's Explanatory Dictionary

Husband. in general, every air phenomenon, everything that is discernible in the world-face, the atmosphere; water: rain and snow, hail, fog, etc. fire: thunderstorm, pillars, balls and stones; air: winds, whirlwinds, haze; light: rainbow, union of the sun, circles around the moon, etc.... ... Dahl's Explanatory Dictionary

Noun, number of synonyms: 19 fireball (2) flash (24) guest from outer space (2) ... Synonym dictionary

meteor- green (Nilus); fiery (Zhadovskaya); dazzling (Nilus); epilepsy (Bryusov); light (Maikov) Epithets of literary Russian speech. M: Supplier of His Majesty's court, the Quick Printing Association A. A. Levenson. A. L. Zelenetsky. 1913 ... Dictionary of epithets

meteor- meteor. Incorrect pronunciation [meteor]... Dictionary of difficulties of pronunciation and stress in modern Russian language

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