Any celestial body that is larger than cosmic dust but inferior to an asteroid is called a meteoroid. A meteoroid falling into the Earth’s atmosphere is called a meteor, while a meteoroid falling onto the Earth’s surface is called a meteorite.

Speed \u200b\u200bin space

The speed of meteoroid bodies moving in outer space can be different, but in any case, it exceeds the second cosmic speed of 11.2 km / s. This speed allows the body to overcome the gravitational attraction of the planet, but it is inherent only in those meteoric bodies that were born in the solar system. For meteoroids that arrive from the outside, higher speeds are also characteristic.

The minimum speed of a meteoroid at a meeting with the planet Earth is determined by how the directions of motion of both bodies relate. The minimum is comparable with the speed of the Earth in orbit - about 30 km / s. This applies to those meteoroids that move in the same direction as the Earth, as if catching up with it. Most of these meteoric bodies, because meteoroids arose from the same rotating protoplanetary cloud as the Earth, therefore, should move in the same direction.

If the meteoroid is moving toward the Earth, then its speed is added to the orbital and therefore is higher. The speed of bodies from a meteor shower called Perseids, through which the Earth passes every year in August, is 61 km / s, and meteoroids from the Leonid stream, with which the planet meets between November 14 and 21, have a speed of 71 km / s.

The highest velocity is typical for cometary fragments, it exceeds the third cosmic velocity - one that allows the body to leave the limits of the solar system - 16.5 km / s, to which it is necessary to add also the orbital velocity and make corrections for the direction of motion relative to the Earth.

Earth meteoroid

In the upper atmosphere, the air almost does not interfere with the movement of the meteor - it is too rare here, the distance between the gas molecules can exceed the size of the average meteorite. But in denser layers of the atmosphere, the friction force begins to influence the meteor, and its motion slows down. At an altitude of 10-20 km from the earth's surface, the body falls into the delay region, losing space velocity and, as it were, freezing in the air.

Subsequently, the resistance of atmospheric air is balanced by Earth's gravity, and a meteor falls on the surface of the Earth like any other body. In this case, its speed reaches 50-150 km / s, depending on the mass.

Not every meteor reaches the earth's surface, becoming a meteorite, many burn out in the atmosphere. You can distinguish a meteorite from an ordinary stone by a melted surface.

Tip 2: What harm can an asteroid flying close to Earth do?

The probability of a meeting of the Earth with a large asteroid is rather small. Nevertheless, it cannot be completely excluded, a slightly higher probability of an asteroid flying near our planet. Despite the fact that there is no direct collision in this case, the appearance of an asteroid near the Earth still carries a number of threats.

During its existence, the Earth has already encountered asteroids, and each time this led to dire consequences for its inhabitants. More than one and a half hundred craters have been discovered on the surface of the planet, the diameter of some of them reaches 100 km.

The fact that the fall of a large asteroid will lead to catastrophic destruction is well understood by any sane person. It is no coincidence that scientists from leading countries of the world have been tracking the flight paths of the most dangerous space bodies for decades, and are developing options to counter the asteroid threat.

One of the most dangerous for earthlings is the asteroid Apophis (Apophis), according to forecasts, it will approach the Earth in 2029 at a distance of 28 to 37 thousand kilometers. This is 10 times less than the distance to the moon. And although scientists claim that the collision probability is negligible, such a close passage of the asteroid can be serious for the planet.

The size of Apophis is relatively small, its diameter is only 270 meters. But every asteroid is surrounded by a whole cloud of small particles, many of which can harm spacecraft launched into orbit. At speeds reaching several tens of kilometers per second, even a speck of dust can cause serious damage. Apophis will pass there, geostationary satellites, it is to them that its small fragments threaten them the most.

Some of the material of asteroids flying near the Earth can fall on its surface, this also conceals its own. Scientists suggest that it is comets that can transfer microscopic organisms from one planet to another. The probability of this is small, but it cannot be completely ruled out.

Despite the fact that the wreckage of a celestial wanderer that has entered the planet’s atmosphere is heated to high temperature, some organisms may well survive. And this, in turn, is a very big threat to all life on Earth. Microorganisms alien to the earth's flora and fauna can become deadly and with rapid reproduction lead to the death of mankind.

Such scenarios look very unlikely, but in reality they are quite possible. Earth medicine still fails to cope even with the flu, which annually leads to the deaths of hundreds of thousands of people. Now imagine a microorganism that has dozens of times higher mortality, multiplies rapidly and can spread easily. His appearance in a large city will be a real disaster, as it will be very difficult to keep the epidemic that has begun.

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3. FLIGHT OF METEORS IN THE EARTH ATMOSPHERE

Meteors appear at altitudes of 130 km and lower and usually disappear at an altitude of 75 km. These boundaries vary depending on the mass and speed of meteor bodies penetrating the atmosphere. Visual definitions of the heights of meteors from two or more points (the so-called corresponding) refer mainly to meteors of the 0-3rd magnitude. Taking into account the influence of rather significant errors, visual observations give the following values \u200b\u200bof meteor heights: height of occurrence H 1  \u003d 130-100 km, altitude of extinction H 2  \u003d 90 - 75 km, the height of the middle of the path H 0  \u003d 110 - 90 km (Fig. 8).

Fig. 8. Heights ( H) meteor phenomena. Height limits  (left): the beginning and end of the car race ( B), meteors from visual observations ( M) and from radar observations ( RM), telescopic meteors from visual observations ( T); (M T) - meteorite delay region. Distribution curves  (on right): 1 - the middle of the path of meteors by radar observations, 2   - the same according to photographic data, 2a  and 2b  - the beginning and end of the path according to photographic data.

Much more precise photographic definitions of heights refer, as a rule, to brighter meteors, from -5th to 2nd magnitude, or to the brightest parts of their trajectories. According to photographic observations in the USSR, the heights of bright meteors are 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 to determine separately H 1  and H 2  only for the brightest meteors. According to the 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 refers only to that part of the meteor trajectory along which a fairly intense ionization trail is formed. Therefore, for the same meteor, the height according to photographic data can significantly differ from the height according to radar data.

For weaker meteors, using a radar it is possible to determine statistically only their average height. The distribution of the average altitudes of meteors mainly of the 1-6th magnitude obtained by the radar method is shown below:

Considering the actual material for determining the heights of meteors, it can be established that according to all the data, the vast majority of these objects are observed in a zone of altitude of 110-80 km. In the same zone, telescopic meteors are observed, which according to A.M. Bakharev have heights H 1  \u003d 100 km H 2  \u003d 70 km. However, according to telescopic observations, I.S. Astapovich and his employees in Ashgabat, a significant number of telescopic meteors are also observed below 75 km, mainly at altitudes of 60-40 km. These are, apparently, slow and therefore weak meteors, which begin to glow only deeply crashing into the earth's atmosphere.

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

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

Geocentric Speed \u200b\u200b( V g)	20	30	40	50	60	70 km / s
Average height ( H 0)	68	77	82	85	87	90 km

At the same geocentric speed of meteors, their heights depend on the mass of the meteoroid. The larger the mass of the meteor, the lower it penetrates.

The visible part of the trajectory of the meteor, i.e. the length of its path in the atmosphere is determined by the values \u200b\u200bof the heights of its appearance and disappearance, as well as the slope of the trajectory to the horizon. The steeper the slope of the trajectory to the horizon, the shorter the visible path length. The length of the path of ordinary meteors does not exceed, as a rule, several tens of kilometers, but for very bright meteors and fireballs it reaches hundreds, and sometimes thousands of kilometers.

Fig. 10. Anti-aircraft attraction of meteors.

Meteors shine on a short visible segment of their trajectory in the Earth’s atmosphere with a length of several tens of kilometers, which they fly in a few tenths of a second (less often in a few seconds). On this segment of the trajectory of the meteor, the effect of the Earth's attraction and deceleration in the atmosphere is already manifested. When approaching the Earth, the initial speed of the meteor increases due to gravity, and the path is bent so that the observed radiant shifts to its zenith (zenith is a point above the observer’s head). Therefore, the effect of the Earth’s attraction on meteor bodies is called anti-aircraft attraction (Fig. 10).

The slower the meteor, the greater the influence of anti-aircraft 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 gravity of the Earth, and Δz- maximum value of anti-aircraft 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 Earth’s atmosphere, the meteoroid also experiences inhibition, at first almost imperceptible, but very significant at the end of the path. According to Soviet and Czechoslovak photographic observations, braking can reach 30-100 km / sec 2 on the final segment of the trajectory, while braking ranges from 0 to 10 km / sec 2 along most of the trajectory. Slow meteors experience the greatest relative velocity loss in the atmosphere.

The apparent geocentric speed of meteors, distorted by anti-aircraft attraction and braking, is accordingly corrected taking into account the influence of these factors. For a long time, the speeds of meteors were not known exactly enough, since they were determined from low-precision visual observations.

The photographic method for determining the speed of meteors using an obturator is the most accurate. Without exception, all meteor speed determinations obtained by the photographic route in the USSR, Czechoslovakia and the USA show that meteor bodies should move around the Sun along closed elliptical paths (orbits). Thus, it turns out that the vast majority of meteor matter, if not all of it, belongs to the solar system. This result is in excellent agreement with the radar data, although the photographic results are on average related to brighter meteors, i.e. to larger meteor bodies. The distribution curve of meteor velocities found using radar observations (Fig. 11) shows that the geocentric speed of meteors lies mainly in the range from 15 to 70 km / s (a number of speed determinations exceeding 70 km / s are due to unavoidable observation errors ) This once again confirms the conclusion that meteor bodies move around the Sun in ellipses.

The fact is that the speed of the Earth in orbit is 30 km / s. Consequently, oncoming meteors with a geocentric speed of 70 km / s move relative to the Sun at a speed of 40 km / s. But at a distance of the Earth, the parabolic speed (i.e. the speed necessary for the body to be carried along the parabola beyond the limits of the Solar System) is 42 km / s. Therefore, all meteor velocities do not exceed parabolic and, therefore, their orbits are closed ellipses.

The kinetic energy of meteorites invading the atmosphere with a very high initial velocity is very high. Mutual collisions of molecules and atoms of a meteor and air intensively ionize gases in a large volume of space around a flying meteoroid. Particles, torn in abundance from a meteoroid, form around it a brightly luminous shell of hot vapors. The glow of these vapors resembles the glow of an electric arc. The atmosphere at heights where meteors appear is very rarefied, so the process of reuniting electrons detached from atoms lasts quite a while, causing a luminescence of a column of ionized gas, which lasts for several seconds and sometimes minutes. Such is the nature of self-luminous ionization traces that can be observed in the sky after many meteors. The luminescence spectrum of the wake also consists of lines of the same elements as the spectrum of the meteor itself, however, they are already neutral and not ionized. In addition, atmospheric gases also glow in the tracks. This is indicated by those discovered in 1952-1953. in the spectra of the meteor trace of the line of oxygen and nitrogen.

The spectra of meteors show that meteor particles either consist 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 make it possible to estimate their size and mass. The visible radius of the luminous shell of meteors of the 1-3st magnitude is estimated at about 1-10 cm. However, the radius of the luminous shell, determined by the spread of luminous particles, far exceeds the radius of the meteoroid itself. Meteor bodies flying into the atmosphere at a speed of 40-50 km / s and creating the phenomenon of meteors of zero magnitude have a radius of about 3 mm and a mass of about 1 g. The brightness of meteors is proportional to their mass, so the mass of a meteor of some magnitude is 2. 5 times less than for meteors of the previous magnitude. 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 velocity, meteor particles are found at altitudes of 80 km and more with a very rarefied gaseous medium. The air density here is hundreds of millions of times lower than at the surface of the Earth. Therefore, in this zone, the interaction of the meteoroid with the atmosphere is expressed in the bombardment of the body by individual molecules and atoms. These are molecules and atoms of oxygen and nitrogen, since the chemical composition of the atmosphere in the meteor zone is approximately the same as at sea level. Atoms and molecules of atmospheric gases during elastic collisions either bounce off or penetrate the crystal lattice of a meteoroid. The latter quickly heats up, melts and evaporates. The rate of particle evaporation is initially negligible, then increases to a maximum and again decreases towards the end of the visible meteor path. Evaporating atoms fly out of the meteor at speeds of several kilometers per second and, having great energy, experience frequent collisions with air atoms, leading to heating and ionization. A red-hot cloud of vaporized atoms forms a luminous meteor shell. Some of the atoms completely lose external electrons during collisions, as a result of which a column of ionized gas with a large number of free electrons and positive ions forms around the trajectory of the meteor. The number of electrons in the ionized trace is 10 10 -10 12 per 1 cm of path. The initial kinetic energy is spent on heating, luminescence and ionization in approximately 10 6:10 4: 1 ratio.

The deeper the meteor penetrates into the atmosphere, the denser its hot shell becomes. Similar to a very fast flying projectile, a meteor forms a head shock wave; this wave accompanies the meteor during its movement in the lower layers of the atmosphere, and in layers below 55 km it causes sound phenomena.

Traces remaining after a meteor flight can be observed both by radar and visually. Especially successfully, one can observe the ionization traces of meteors in high-aperture binoculars or telescopes (the so-called comet detectors).

Traces of fireballs penetrating into the lower and denser layers of the atmosphere, on the contrary, mainly consist of dust particles and are therefore visible as dark smoky clouds against a blue sky. If such a dusty trail is illuminated by the rays of the setting sun or moon, it can be seen as silvery stripes against the background of the night sky (Fig. 12). Such traces can be observed for hours until they are destroyed by air currents. Traces of less bright meteors, forming at altitudes of 75 km and more, contain only a very small fraction of dust particles and are visible solely due to the self-luminescence of the atoms of the ionized gas. The duration of visibility of the ionization trail with the naked eye is 120 seconds for fireballs of the 6th magnitude, and 0.1 sec for the 2nd magnitude meteor, while the duration of the radio echo for the same objects (at a geocentric speed of 60 km / sec) is equal to 1000 and 0.5 sec. respectively. The fading of ionization traces is partially due to the attachment of free electrons to oxygen molecules (O 2) contained in the upper atmosphere.

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

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

Space body size

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

Composition

Small bodies of the solar system can have different composition and density. Therefore, there is a difference whether a stone or iron meteorite will fall on the Earth, or if the comet’s core is loose, consisting of ice and snow. Accordingly, in order to cause the same damage, the comet's nucleus should be two to three times larger than an asteroid fragment (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 bodies. After all, there is a transition of kinetic energy of motion into heat. And the speed of entry of cosmic bodies into the atmosphere can vary significantly (from about 12 km / s to 73 km / s, for comets - even more).

The slowest meteorites are those catching up with the Earth or catching up with it. Accordingly, those flying towards us will add up their speed with the orbital speed of the Earth, will pass through the atmosphere much faster, and the explosion from their impact on the surface will be several times more powerful.

Where will fall

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

A meteorite can fall at a place of storage of a nuclear weapon or at a nuclear power plant, then environmental damage can be greater from contamination with radioactive substances than from a meteorite impact (if it was relatively small).

Angle of incidence

Does not play a big role.  At those tremendous speeds at which the cosmic body crashes into the planet, it does not matter at what angle it will fall, since in any case the kinetic energy of the motion will go into the thermal and will be released in the form of an explosion. This energy does not depend on the angle of incidence, but only on mass and speed. Therefore, by the way, all the craters (on the Moon, for example) have a circular shape, and there are no craters at all in the form of some trenches drilled at an acute angle.

How do bodies of different diameters behave when they fall to Earth

Up to a few centimeters

They burn out completely in the atmosphere, leaving a bright trace several tens of kilometers long (a well-known phenomenon called meteor) The largest of them reach altitudes of 40-60 km, but most of these "dust particles" burn out at an altitude of more than 80 km.

Mass phenomenon - within just 1 hour, millions (!!) meteors flare up in the atmosphere. But, taking into account the brightness of the flashes and the radius of the observer's view, at night in one hour you can see from a few to dozens of meteors (during meteor showers - more than a hundred). For a day, the mass of dust deposited on the surface of our planet from meteors is calculated in hundreds, and even in thousands of tons.

From centimeters to several meters

Fireballs  - the brightest meteors, the brightness of the flash of which exceeds the brightness of the planet Venus. The flash may be accompanied by noise effects up to the sound of an explosion. After that, a smoky trail remains in the sky.

Shards of cosmic bodies of this size reach the surface of our planet. It happens like this:

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

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

If the rate of entry into the atmosphere was very high (oncoming trajectory), then such meteoroids are much less likely to fly to the surface, since the force of their friction against the atmosphere will be much greater. The number of fragments into which the meteoroid can be split can reach hundreds of thousands, the process of their falling is called meteor Rain.

In a day, several tens of small (about 100 grams) fragments of meteorites can fall to the Earth in the form of cosmic precipitation. Given that most of them fall into the ocean, and in general, they are difficult to distinguish from ordinary stones, they are rarely found.

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

17 meters - Chelyabinsk car

Superbolid  - this is what is sometimes called especially powerful explosions of meteoroids, similar to the one that exploded in February 2013 over Chelyabinsk. The initial size, which then entered the atmosphere of the body according to various expert estimates, varies, on average, it is estimated at 17 meters. Mass - about 10,000 tons.

The object entered the Earth’s atmosphere at a very sharp angle (15–20 °) at a speed of about 20 km / s. He exploded after half a minute at an altitude of about 20 km. The power of the explosion was several hundred kilotons of TNT. This is 20 times more powerful than the Hiroshima bomb, but the consequences here were not so fatal because the explosion occurred at a high altitude and the energy dissipated over a large area, to a large extent, far from settlements.

Less than a tenth of the initial mass of the meteoroid flew to Earth, that is, about a ton or less. The fragments scattered over an area more than 100 long and about 20 km wide. Many small fragments were found, several kilograms in weight, the largest piece weighing 650 kg was lifted from the bottom of Lake Chebarkul:

Damage:  nearly 5,000 buildings were damaged (mostly broken glass and frames), about 1,500 people were injured by shattered glass.

A body of this size could well reach the surface without falling apart into fragments. This did not happen because of the too sharp angle of entry, because before exploding, a meteoroid flew in the atmosphere several hundred kilometers. If the Chelyabinsk meteoroid fell vertically, instead of an air shock wave that broke the glass, there would have been a powerful blow to the surface, which entailed a seismic shock, with the formation of a crater with a diameter of 200-300 meters. About the damage and the number of victims, in this case, judge for yourself, everything would depend on the place of the fall.

Concerning repetition rates  of such events, then after the Tunguska meteorite of 1908 - this is the largest celestial body that fell to Earth. That is, in one century one or more of such guests from outer space can be expected.

Tens of meters - small asteroids

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

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

If an asteroid, even the smallest, encounters the Earth, then it definitely will not fall apart in the atmosphere and its speed will not slow down to the rate 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, it will turn into thermal energythat will melt the asteroid itself, and mechanical, which will create a crater, scatter around the rock and fragments of the asteroid itself, and also create a seismic wave.

To quantify the magnitude of such a phenomenon, we can consider for example an asteroid crater in Arizona:

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

Another event of comparable scale is the Tunguska meteorite. The power of the explosion was 3,000 Hiroshim, but there was a fall of a small cometary nucleus with a diameter of tens to hundreds of meters, according to various estimates. The nuclei of comets are often compared with dirty snow cakes, so in this case no crater arose, the comet exploded in the air and evaporated, knocking down a forest in an area of \u200b\u200b2 thousand square kilometers. If the same comet exploded over the center of modern Moscow, it would destroy all houses right up to the ring road.

Fall frequency asteroids tens of meters in size - once every several centuries, hundred-meter - once every several thousand years.

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

Although according to the latest NASA data, the probability of the Apophis asteroid falling into the Earth when it flies near our planet in 2029, and then in 2036 is practically zero, nevertheless we will consider the scenario of the consequences of its possible fall, since there are many as yet undiscovered asteroids, and a similar event can still occur, not this time, but another time.

So .. the asteroid Apophis, contrary to all forecasts, falls to Earth ..

The power of the explosion is 15,000 Hiroshima atomic bombs. When it hits the mainland, an impact crater with a diameter of 4-5 km and a depth of 400-500 meters occurs, the shock wave demolishes all brick buildings in a zone with a radius of 50 km, less durable structures, as well as trees lying at a distance of 100-150 kilometers from the place fall. A pillar of dust like a mushroom from a nuclear explosion several kilometers high rises into the sky, then the dust begins to spread in different directions, and within a few days spreads evenly throughout the planet.

But, in spite of the greatly exaggerated horror stories that the media usually scare people, a nuclear winter and the end of the world will not come - the Apophis caliber is not enough for this. According to the experience of powerful volcanic eruptions in a not very long history, during which huge emissions of dust and ash also take place in the atmosphere, with such a power of the explosion, the “nuclear winter” effect will be small - the average temperature on the planet will drop by 1-2 degrees, after Six months to a year, everything returns to its place.

That is, this is a disaster not of a global but of a regional scale - if Apophis gets into a small country, he will completely destroy it.

When Apophis enters the ocean, coastal areas will suffer from the tsunami. The height of the tsunami will depend on the distance to the place of impact - the initial wave will have a height of about 500 meters, but if Apophis falls into 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 the waves will be several hours. If a blow to the ocean occurs near the coast, then surfers in coastal (and not only) cities will be able to ride on such a wave: (sorry for the black humor)

Recurrence rate  events of a similar scale in the history of the Earth are measured in tens of thousands of years.

We turn to global disasters ..

1 kilometer

The scenario is the same as during the fall of Apophis, only the scale of the consequences is several times more serious and already reaches the global catastrophe of a low threshold (the consequences are felt by all of humanity, but there is no threat of the death of civilization):

Explosion power in "Hiroshima": 50,000, the size of the crater formed when falling to land: 15-20 km. The radius of the destruction zone from the blast 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 appear will be very high (1-2 km), but not long, and such waves will decay quite quickly. But in any case, the area of \u200b\u200bflooded territories will be huge - millions of square kilometers.

Reducing the transparency of the atmosphere in this case from emissions of dust and ash (or water vapor when falling into the ocean) will be noticeable for several years. If it gets into a seismically dangerous zone, the consequences can be aggravated by earthquakes provoked by the explosion.

However, an asteroid of this diameter will not be able to tilt the Earth's axis noticeably or affect the period of rotation of our planet.

Despite the dramatic nature of this scenario, for the Earth it is a rather ordinary event, since it has already happened thousands of times during its existence. Average recurrence  - once every 200-300 thousand years.

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

• Explosion power in Hiroshima: 50 million
• The size of the crater formed when falling to land: 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 crust under the plains is an average of 35 km). The exit of magma to the surface will begin.
• The area of \u200b\u200bthe destruction zone can be several percent of the Earth’s area.
• In an explosion, a cloud of dust and molten rock rises to a height of tens of kilometers, possibly up to hundreds. The volume of discarded materials - several thousand cubic kilometers - is enough for a light “asteroid fall”, but not enough for a “asteroid winter” and the beginning of the ice age.
• Secondary craters and tsunamis from fragments and large pieces of discarded rock.
• A small, but by geological standards, a decent slope of the earth's axis from the impact - up to 1/10 of a degree.
• When entering the ocean - a tsunami with kilometer (!!) waves extending far deeper into the continents.
• In the case of intense eruptions of volcanic gases, acid rain is possible afterwards.

But this is still not quite Armageddon! Even such grandiose catastrophes, our planet has experienced tens or even hundreds of times. On average, this happens alone. once every 100 million years.  If this happened now, the number of victims would be unprecedented, in the worst case it could be measured in billions of people, moreover, it is not known what social shocks this would lead to. However, despite the period of acid rain and several years of some cooling due to a decrease in the transparency of the atmosphere, in 10 years the climate and biosphere would have completely recovered.

Armageddon

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

The next ice age will come, most of the living organisms will die, but life on the planet will continue, although it will not be the same as before. As usual, the fittest will survive ..

Such events have also happened more than once. From the moment of the appearance of life on it, armageddons have occurred at least several, and perhaps dozens of times. It is believed that the last time this happened 65 million years ( Chiksulubsky meteorite), when dinosaurs and almost all other species of living organisms died, only 5% of the elect remained, including our ancestors.

Full Armagedets

If a cosmic body the size of the state of Texas crashes into our planet, as was the case in the famous film with Bruce Willis, then even bacteria (although who knows?) Will not survive, life will have to arise and evolve again.

Conclusion

I wanted to write a review post about meteorites, but I got Armageddon's scripts. Therefore, I want to say that all the events described, starting with Apophis (inclusive), are considered as theoretically possible, since in the next hundred years they will definitely not happen. Why so - is described in detail in a previous post.

I also want to add that all the numbers given here regarding the correspondence of the size of the meteorite and the consequences of its fall to Earth are very approximate. The data in different sources differ, plus the initial factors during the fall of an asteroid of the same diameter can vary greatly. For example, everywhere it is written that the size of the Chiksulubsky meteorite is 10 km, but in one, it seemed to me, an authoritative source, I read that a 10-kilometer stone of such troubles could not have done, so my Chiksulubsky meteorite entered the 15-20 kilometer category .

So, if suddenly Apophis still falls in the 29th or 36th year, and the radius of the affected area will be very different from what is written here - write, I’ll fix it

The speed of a meteorite body that falls to the Earth, flying from the deepest depths of space, exceeds the second cosmic velocity, whose rate is eleven point and two tenths of a kilometer per second. This meteorite speedequal to that which needs to be given to the spacecraft in order to break out of the gravitational field, that is, this speed is acquired by the body due to the attraction of the planet. However, this is not the limit. Our planet is moving in orbit at a speed of thirty kilometers per second. When a moving object of the solar system crosses it, it can have a speed of up to forty-two kilometers per second, and if a celestial wanderer moves along an oncoming path, that is, head to head, then he can collide with the Earth at a speed of up to seventy-two kilometers per second . When a meteorite body enters the upper atmosphere, it interacts with rarefied air, which does not interfere much with the flight, almost without creating resistance. At this point, the distance between the gas molecules is larger than the size of the meteorite itself and they do not interfere with the flight speed, even if the body is quite massive. In the same case, if the mass of the flying body is at least slightly greater than the mass of the molecule, then it slows down already in the uppermost layers of the atmosphere and begins to settle under the action of gravity. That is how about a hundred tons of cosmic matter settles on the Earth in the form of dust, and only one percent of large bodies nevertheless reach the surface.

So, at a height of one hundred kilometers, a freely flying object begins to slow down under the action of friction that occurs in the dense layers of the atmosphere. A flying object encounters strong air resistance. The Mach number (M) characterizes the motion of a solid in a gaseous medium and is measured by the ratio of the speed of the body to the speed of sound in the gas. This number M for a meteorite is constantly changing with height, but most often does not exceed fifty. A rapidly flying body forms an air cushion in front of itself, and compressed air leads to the appearance of a shock wave. The compressed and heated gas in the atmosphere heats up to a very high temperature and the surface of the meteorite begins to boil and spray, taking away the molten and remaining solid material, that is, the ablation process takes place. These particles shine brightly, and the phenomenon of a car, leaving a bright mark. The compression region that arises in front of a meteorite rushing at a tremendous speed diverges to the sides and a head wave is formed, similar to the one that comes from the ship’s running occasion. The resulting cone-shaped space forms a wave of turbulence and rarefaction. All this leads to a loss of energy and causes increased inhibition of the body in the lower layers of the atmosphere.

It may happen that the speed a is from eleven to twenty-two kilometers per second, its mass is not large, and it is mechanically strong enough, then it can slow down in the atmosphere. This contributes to the fact that such a body is not subject to ablation, it can almost invariably fly to the surface of the Earth.

With a further decrease in air more and more slows down meteorite speedand at a height of ten - twenty kilometers from the surface, he completely loses cosmic speed. The body, as it were, hangs in the air, and this part of the long journey is called the delay region. The object gradually begins to cool and ceases to glow. Then, all that remains of a difficult flight falls vertically to the surface of the Earth under the force of attraction at a speed of fifty to one hundred and fifty meters per second. In this case, gravity is compared with air resistance, and the heavenly messenger falls like an ordinary thrown stone. It is this meteorite velocity that characterizes all objects that have fallen to the Earth. In the place of the fall, as a rule, depressions of different sizes and shapes are formed, which depends on the weight of the meteorite and the speed with which it approached the surface of the soil. Therefore, studying the place of the fall, we can say for sure what was the approximate meteorite speedat the time of collision with the Earth. A monstrous aerodynamic load gives the celestial bodies that came to us, characteristic features by which they can be easily distinguished from ordinary stones. They form a melting crust, the shape is most often conical or fused-clastic, and the surface as a result of high-temperature atmospheric erosion receives a unique remhalipt relief.

Cosmos is a space filled with energy. The forces of nature make chaotically existing matter group. Objects are formed with a specific shape and structure. Planets, their satellites, have long been formed in the solar system, but this process does not end. A huge amount of substance: dust, gas, ice, stone and metal, fill the space. These objects are classified.

A body no larger than a dozen meters in size is called a meteoroid; a larger body can be considered an asteroid. A meteor is an object burning in the atmosphere, falling to the surface, it becomes a meteorite.

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

Celestial bodies inevitably collide with each other. The moon has preserved the result of millions and millions of years of interaction. On earth, huge craters say that once, global destruction occurred. People always strive for control; all potential threats must have methods and technologies to eliminate them. The obvious option with the use of nuclear weapons is ineffective. Most of the explosion energy is simply dissipated in space. It is extremely important to detect a dangerous lump as early as possible, which does not always work out. The good thing is that the larger the body, the easier it is to detect.

Tons of cosmic dust fly into the atmosphere every day, at night you can watch how small meteoric bodies burn up with the so-called “falling stars”. Each year, meteoroids up to several meters in size fall into the airspace of our planet. A meteorite can enter the atmosphere at a speed of 100,000 km / h. At an altitude 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 are given for meteorites of the solar system, vagrants from outside develop an order of magnitude greater speed.

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

Meteorites are divided into stone and iron. The composition always includes a mixture of elements with a variety of proportional proportions. The structure may be heterogeneous with intersperses. Metal alloy of iron meteorites of excellent quality, suitable for the manufacture of all kinds of products.